I would personally do a larger rack with a wide variety of tubs that will fit in it. I did the measurements a while back, so i forgot the exact dimensions. But you can fit a 28 qt sterilite and a 12 qt sterilite tub side by side and it equals the length of a 41 qt long ways. Do some reasearch and with about 4 sheets of melamine, you can make one sick nasty rack with 6 or 7 shelfs that can posslibly hold 21 15 qt tubs, 7 28qts and 7 15 qts, or just 7 41 qt tubs.

If i can tell you one thing, when you own a bunch of different sizes of ball pythons, trying to find the right tub and not having to have a whole new rack for it. Right now i have an 8 shelf rack that holds 2 15 qts or 1 28 qt and i love how i have so many options. Just this week i am having a 5 tub 41 qt rack being built for me and i feel this will solve my problems for having 2300 gram females and 230 gram juveniles in a reasonable amount of space.

Even though your going to have a few more snakes than i do, i hope you can find the perfect setup to hold all your animals and just using a long strip of flexwatt down the back or on the belly. Just get a thermostat with a 6 repceptacle input and use either 3 inch or 11 inch flexwatt for the heating, you can't go wrong and will most likely cost you under $350 for homes for over 20 snakes.