Can you go a bit more in height??? If so, a 36x18x24 exo terra enclosure would be fine for a Green Tree Python. So many folks think they are difficult to care for when they really are not. Sure, they're perhaps a bit more touchy than a BP, but if the BP is the volkswagon of the snake world, a GTP is only a mustang and NOT a maserati (as far as care and maintainence is concerned - I do consider them a luxury snake to own, lol). If you can maintain about 70% humidity for them with the additional misting each morning, you'll be fine! Exo Terras hold humidity really well - they're designed for it.

I don't know what the care requirements are for a beauty snake or a vine snake, but I know they aren't particularly large. Why do you think it wouldn't be possible to have one?? I say, if that's what you really want, then work towards it!