Perko/Batt Switch on the Floor? 99 Super Air

I've got a Perko Switch in the box I'd like to stick in the boat tomorrow night.

We don't leave the boat in the water but it will sit at the lake in the barn or driveway for a few weeks on ocassion so I like to be able to disconnect the batteries.

I found someone that had mounted their switch to the floor under one of the back seats. I assume moisture might be a concern but since these are engineered to be used in a damp environment I guess it "should" be fine. Any input?

Also, anybody else with an older super air with the electric hatch have a suggestion? I'd like the switch to be outside of the engine compartment so I can access it without power :)

Also Battery mounting Suggestions with two batteries? I've got boxes in there now but they are taking up floor space for ballast bags.

Thank you,

Trey