Sup Mike,
I placed my transducer in my rear hatch (toward the rear scupper holes). That way, it's out of the way. Take some sand paper and rough out the spot where you're going to place the transducer. Get some Marine Goop from West Marine, or a similar store. Goop the bottom of the transducer with a lot of goop and place a brick, or something heavy to keep it from sliding during the settling time. There should be a flat section along the length of the boat (keel?). As for the for the bait tank, just hook up an on/off switch.. I like it, because it's cheap. That toggle switch to the left of my hatch is my on/off switch for my bait tank.
I've had my transducer in the same spot, launched LJ plenty of times, and still it's still stuck...
Hope this helps, Dennis