For my latest trick, I subdivided Wiggles's tub with a cardboard sheet.
Under the cardboard, he has a hide and some cardboard tubes with newspaper for substrate. Above the cardboard, he has a large water tray, another hide and a temp/humidity gauge with repticarpet for substrate.
Besides just giving Wiggles another level to explore, I theorize that the cardboard will help trap the heat from the heat mat raising the ambient heat on the lowest level and the water vapor from the tub raising the humidity on the higher level. I, also, think it looks nicer than when it was just full of junk. Time will tell if Wiggles is as pleased with it as I am.