[PerryC]

TG,
Alot of electronic whatevers sold as "waterproof" are really "water-resistant" in the real world. I dunno if it's labeling error or intentional some of the times. Most switches are NOT 100% waterproof. If they are installed to be waterproof/water-resistent, water will not under normal circumstances be able to contact the connection blades of the switch and it will have a rubber cover over the button or toggle to keep splash water from entering the internals.

You may not want to go this route, but I keep any switches inside an enclosure of some type like a waterproof box or in the dry bag with the battery. Looks plain Jane and you have to open something to access the switch, but I'll turn it on and leave it on all day so I'm not turning it off and on constantly.

For a anti-siphon valve, I would call the guys at Hooked On Kayaks in Huntington Harbor. They are the old Malibu Kayaks store. I was in there a few weeks ago and I believe they had the individual parts for making bait tanks for sale. The valve they use on their bait tanks works pretty good. Their phone is 562-592-0800 . Andy who runs the shop would probably be the best one to talk to as I think he has used a powered bait tank the most. Hope this helps,
Perry