I have my snakes in a rack system and use only one hide on the warm side.
Moist hides??? Like a moss box or something?? I wouldn't, you would chance scale rot if they hung out in there too much. If you need more humidity just spritz the cages.
I use a rack system in the basement with a space heater. The room humidity is 30%, but the tubs stay an almost constant 60% with the water bowls on the cool side.