Guernsey closed the gap on London South One leaders Chichester to four points after an impressive 51-15 win at mid-table Beckenham.
Andy Bailey, Blair Campbell, Malcolm Barnes, Darren Bellingham, Sam Stevens, Nick Barton and Luke Jones all scored a try each as Guernsey got a bonus point.
Luke Sayer kicked 12 points while Barton added two conversions.
Chichester failed to get a bonus point as they edged past fourth-placed Basingstoke 15-14 to stay top.
The two sides face each another on 24 March.