There are ways of getting the humidity to stay. Some, like I have before use saran wrap around the plastic tubes but I say experiment. I only see the problem being that you say you wanna put more than what seemed to be a pair in it. I would just stick to a male and a female and sometimes that even may get hairy.

Also use lots of live plants and such like pothos. keep them in the pots along the bottom and keep them watered good. This will help create some good humidity but try your best at getting some big pots.

Oh one other problem is using a UTH on them is almost impossible. I eventually switched to glass for this reason. Using a good size UTH on the bottom with a good substrate that stays moist will help humidity greatly in this case.