Well, I've heard of folks breeding them in 632 Visions but that sure seems tight to me. I'd think 8x4x2.5 feet is a more reasonable minimum. I built them that size for my monitors (I savanna, 1 Dumerils - they were stacked like bunkbeds) I like the extra height so you can give them a foot of substrate and still have headroom for some low rocks & logs for them.