I wrote a long post about this issue (with pictures) a couple of weeks ago. I'm on the Tapatalk app right now and don't know how to link a post but if you search my username or just 12v you should find it. Short answer- on my trailer, NO cutting off the switch wasn't even close to cutting off 'everything'. I did some major rewireing.
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Buddy Ray - Atlanta
Jayco 2016 Eagle HT 26.5RLS
Ford 2016 F150 Lariat, 3.5L V6 Ecoboost
Max Tow Pkg, 36gal tank
Reese Sidewinder and Reese Titan 16k hitch