I'd say a che, but it will kill the humidity lol. So in that case I'd just put a little humidity box with some damp moss inside, with a lid and a hole cut out so the snake can go in and out as it pleases. I personally use rhp's in my PVC cages and flexwatt in my racks controlled with good thermostats because most rheostats are junk and I absolutely hate using bulbs and aquariums lol.