If you have bigger snakes, I would go with the 41qt. As for the heat tape, I would go on the shelf for belly heat. Aluminum foil tape will hold it down just fine. I have a two racks, one with back heat (from RBI) and one with belly heat (I built). I think I prefer the belly heat. RBI is a great place to order it from. I just order some more Monday morning and got it yesterday.
And topless is the way to go!