I'm in the process of building a new multi-sized rack and I've come up on a small issue. Because this new rack is going to be four feet wide, I definitely need to have some kind of support along the back side to keep it from sagging in the middle. I'm debating between using another pair of 2x4's to basically give it another set of legs in the back, or getting a sheet of thin wood to enclose the entire back end. I like the idea of enclosing the back end of it, since it seems to me that doing so will let me keep heat in a little easier. Mind you, I live in north Texas and I don't usually have to worry about my temps dropping too low. Keeping an ambient 80 degrees in my snake room is incredibly easy, even now in the coldest part of winter. I may even end up having the opposite problem of trying to keep my temps down low enough during the summer, so I can do with or without the extra insulation. Another thing that may influence my decision will be how I want to heat this new rack. Due to some fun outside circumstances, I'm going to be getting all my flexwatt with my next paycheck, which won't be for another two weeks. If I choose to close up the back, I have the option of placing the heat tape along the back of the rack instead of using it as belly heat. Because of the way I designed this new rack, hatchlings and juveniles would still have the heating in the back like normal, but adult tubs have to go in sideways so the heating on these tubs would be along the long side.

The questions:
1) Does the longways heating of the adult tubs matter? How would back vs. belly heat affect the adult tubs?

2) Which methods would be better for this build? Belly or back heat?

3) Should I go ahead and enclose the back end, or will bonus legs be alright? With bonus legs, I won't be able to back heat and will have to use belly heat.

4) I'm also planning on wiring the shelves so I don't have to run all at once (it's going to be 9 slots, so maybe one 4 and a 5? A bunch of 2's and a 3?) but I'm not super familiar with electrical work beyond the parallel wiring I did on my previous rack. Is there an ideal way to be able to connect multiple of these together when I need to run more shelves, or is there a good thermostat that I can plug multiple shelves into? Will I just have to get multiple thermostats to play it safe?

Thanks in advance!