Animal Plastics cage.....optimum size for BP?

[KWenger]

I have decided to order two enclosures for my BPs from Animal Plastics. I currently house my adult male in a 40 gal. breeder tank (36 x 18 x 17) and it seems to be an ideal size. I also have a juvenile male that will be big enough for his "forever" enclosure soon. Problem is keeping the temperature and humidity at correct levels during the wintertime. The room where I keep my snakes goes down to the low-mid 60s during the winter and it is difficult to keep the glass tanks warm enough. And maintaining correct humidity during the winter months is especially difficult. I have an Animal Plastics enclosure for my boa and think the quality is excellent. I plan to order the BPs enclosures with both Flexwatt for belly heat and a RHP (radiant heat panel) to maintain ambiant air temps. Everyone I've talked to assures me it will be MUCH easier to keep humidity levels up with the AP cages too. Now, my question is what size to get? The AP model T1 seems too small (24x24x12) and both the T3 (36x24x12) and T5 (36x24x24) are bigger than I need.....at least that's what I'm thinking. What is your opinion? Animal Plastics will build custom size enclosures and I am considering ordering a couple 36x18x18. Does that sound about right? As long as I'm placing a custom order I can get ANY SIZE I want. If you were starting from scratch with a custom size enclosure, what would you recommend as the "perfect" size for an adult male BP? Thanks!