On a 99 Fever 32 does the cabin power switch, and more specifically the radio draw off one battery or both? Im about to add a 3rd as well as amps and subs and am hoping one is isolated off to keep from drawing all 3 dead.

Just curious where you are planning to put the extra battery? (Considering doing the same in my 32)

It depends on how you have your switches under the seat. Everything will run off the left/passenger side if you have the left switch on 2 & the right on 1. I took out the water tank & mounted a 3rd battery there so the amps/radio always had 2 battaries to draw off of.