Paradise, population one, is halfway along one of the roughest roads in the US West, perched between two vast wilderness areas that total 1.4 million hectares.

We met Earl in the middle of a one-lane dirt road 100km deep in the backcountry. With a coffee cup in hand, wide grin on his weathered face and two black dogs dancing around his boot-clad feet, he reached in the car window to shake our hands.

“You made it to Paradise!” With a glance at the camping gear packed in our truck bed, he added, “I'll show you my favourite campsite, but mind the rattlesnakes. We're a long way from help."

Paradise, population one, is halfway along the Magruder Corridor, one of the roughest roads in the US West. This 163km primitive dirt track winds through the largest wilderness area in the continental US, climbing over steep mountains and crossing snow-fed streams along the Montana and Idaho border.

Along with his dogs, Harrison and Ozzie, 64 year-old Earl is the only permanent resident of this remote outpost during summer. He is the Bitterroot National Forest's camp host, welcoming the motley crew of hikers, hunters, fishermen and river rafters who brave the bumpy, serpentine road. While his primary responsibility is handing out permits to boaters on the Selway River, he also doles out free advice on the must-see trails that lace through the wilderness. And if you ply him with a second cup of coffee, he'll regale you with stories of windsurfing in Puerto Rico, kayaking in New Mexico or a few of his other varied adventures around the globe.

The infamous Magruder Corridor had been on my to-do list for years. Although just a stone's throw from our home in Missoula, Montana, it takes hours to drive there. Perched between the Selway-Bitterroot Wil­derness to the north and the Frank Church-River of No Return Wilderness to the south, the Magruder Corridor is not a route for the faint of heart: it bisects 1.4 million rugged hectares with no services.  

It sounded like heaven to my husband and me. So we packed our two-year-old son into our beat-up pickup truck along with a spare tyre, a handsaw and enough water and food for four days, and set out to explore the area’s wild rivers, lush cedar groves and steep hills.

Finding Earl in Paradise was an unexpected perk.

A retired industrial electrician, Earl has spent nearly three decades backpacking the Selway-Bitterroot Wilderness, often using Paradise as a launch point. On one of his summer trips, the couple who used to host the Paradise campground told Earl they weren't coming back.

“I asked how to apply for the job, and here I am. Six summers and counting. It's a dream come true,” Earl said.

Maintaining dozens of stinky outhouses and hand-sawing through huge logs certainly isn't everyone's idea of a perfect retirement plan. But Earl sees it as a way to live a portion of the year in the place he loves best. 

In return for volunteering, the US Forest Service (USFS) provides Earl with a small food stipend, a work truck and an 80-year-old, one-room log cabin. Earl leaves his other home on the banks of the Mississippi River and heads for Paradise as soon as the snow melts from the Magruder Corridor, which could be as early as May but often isn't until mid-June. His wife joins him for a portion of the summer, but she prefers to stay closer to their kids and grandkids.

Once he arrives, Earl gets to work. He weed whacks around the campsites and clears the trails of fallen branches. And – perhaps most importantly – he greets visitors, introducing them to the opportunities and potential dangers in the surrounding woods. In between work, he plays plenty.

“I still strap on a backpack and take off with Harrison whenever I can,” Earl said, patting the dog's greying muzzle. He showed us photos from past expeditions, including several of him posed precariously atop knife-edge ridges. In the last shot, Earl was standing inside a cave decorated with Native American pictographs.

The corridor hasn't changed much since the Nez Perce Indians travelled this east-west route centuries ago. When gold was discovered in 1861 in Elk City, Idaho, and Bannack, Montana, the traffic increased as traders and miners frequented the trail to navigate between mining outposts. In 1980, the Central Idaho Wilderness Act passed, encompassing the corridor. Usually you don't find roads in America's designated wilderness areas, but the Magruder Corridor was grandfathered in due to its historical value.

Over the centuries, this throughway has gone by many names, its current moniker stemming from a Wild West tale involving an 1863 massacre. But these days, the main dangers along the Magruder Corridor are fallen trees, which often block the road. Enter Earl, who rides to the rescue in his little white truck.

As we sat around the campfire during our first night in Paradise, Earl told us that he'd spent a good chunk of the morning trying to clear out a fir that had fallen across the Paradise Road.

“After about half an hour, I was sweating pretty good. That's when a couple of boaters pulled up. The kids got out, handed me a cold beer, took the saw and finished the job.” He chuckled. “I wasn't going to say no!”

Those same “kids” were the only other campers at Paradise that evening, readying their two lightweight rafts for a four-day, 76km white-water rodeo ride down the Wild and Scenic section of the Selway River. The two strapping 30 year-olds from Idaho planned to launch in the morning. We watched them lay out coolers and drysuits alongside oars and helmets, asking them questions about their gear and letting our son bounce on the rubber rafts.

To float through the heart of the Selway-Bitterroot Wilderness during peak season (15 May to 31 July), boaters must apply for a permit from the USFS. Very few people actually secure one. After the Grand Canyon, the Selway is the second-most difficult river permit to obtain in the Lower 48. Only one party is allowed to launch each day with a maximum of 16 people per group – a system put in place to protect the wilderness' natural resources as well as its unique solitude. 

I could see why the Selway was popular. The run from Paradise to Selway Falls is a wash of green waves framed by soaring canyons and moss-covered trees. Big boulders line the riverbed beneath rushing water, creating Class IV rapids with names like Moose Juice, Double Drop and Little Niagara. In between the rapids, deep pools invite a quick swim in the chilly water or tempt anglers to toss in a line to the waiting trout.

Each week, Earl drives 100km each way to the nearest USFS office to collect a small stack of paper tags that he ties to each boat going down the river. Earl also reports daily on the river's flow level. The “Paradise Gauge” is the holy grail of serious boaters.

“Some of these guys will only put in if it's over 5ft,” Earl explained. “That's when the waves get really big.”

That morning, he said, the Selway had clocked in at 1.5ft. The rapids seemed intimidatingly big to me. I couldn't imagine how angry the river would look with three times the volume.

We said goodnight to Earl and the boaters from Idaho, their lavender permit tags waving like flags in the cool breeze. A cloud of caddisflies flitted over the river, while the rosy light from the high-latitude sunset lingered long past 10pm, fooling us into a later bedtime. Snuggled in our tent, I drifted to sleep to the sound of the river speeding past.  

The next morning, Earl meandered up to our picnic table with his walking stick in hand. Ozzie, his wife's dog, meandered slowly behind him, while Harrison loped laps around the empty campsite. Despite the near-freezing air, Earl wore shorts under his plaid button-down coat. I poured him some coffee, hoping for more stories about Paradise.

As the sun rose over the ridge, burning off the morning chill, Earl reminded us to keep on the lookout for rattlesnakes basking on the warming rocks. Wild temperature swings are common in the Magruder Corridor: mid-summer temps often hover above 35C, but Earl's seen snowstorms in August. As he eyed the puffy clouds and mostly-blue sky, Earl announced it was a good day to take his kayak out for its inaugural summer run.

I raised an eyebrow, still wearing my coat. “Looks like a good way to get hypothermia to me.”

Earl grinned. My husband offered to shuttle him to the start of his river run. “Nah,” Earl replied with a wave of his hand. “Half the fun is riding my motorcycle back from the take-out!”

Over the next three days, we hiked, watched songbirds and caught garter snakes. Our son threw rocks in the river while we lounged on sandy shores. But the highlight of the trip was chatting with Earl. His tales rivalled the scenery, bringing the wilderness and all of its human and animal characters to life.

Next time we visit Paradise, I'll be sure to throw in more coffee and beer to share with Earl. The reward of his company is well worth the extra supplies.

If you liked this story, sign up for the weekly bbc.com features newsletter, called “If You Only Read 6 Things This Week”. A handpicked selection of stories from BBC Future, Earth, Culture, Capital, Travel and Autos, delivered to your inbox every Friday.