Maybe cut some rectangles of pegboard, the wooden stuff, seal it? That would help with the humidity. I did that with my friend's 55 gal. and his snake sheds perfectly everytime. I did it the ghetto way though, made handles out of clothesline, LoL, but it does the job. I was trying to find a good way to hold it down, but couldn't find any good clamps or whatnot to use, so he just put guitar amps on top and Snake doesn't get out.

I'm not sure how you would want to cut out openings for the lamp and other fixture, but I'm sure you could get a jigsaw and cut a circle and another small rectangle out of the pegboard, cover it with screen somehow, secure it with staples. I don't know. Worth a try though. Other than that, maybe get a room humidifier, I've heard Wally World has some for a pretty good price. Hope that helped a little.