I have my new hatchlings in a 15qt tub in my rack, so it's belly heat. As far as substrate, I'm using Reptibark as it holds humidity better than aspen or newspaper. I used a hide in the back over the heat and in the front, I laid out some moss. I did this over the back corners as well. They are both loving life. They bury themselves in the reptibark under the moss and seem very secure and happy. I set them up on Sunday and they both eagerly ate for me on Tuesday.