I'm planning on heating the whole room with a 1500 watt oil filled heater hooked up to a thermostat. I ran 11" flex watt back heat on one of the baby racks before I decided on heating the whole room.
I run 3" flex watt tape on my office rack as belly heat and it works great on 41qt tubs.
If the whole room is heated to a certain temp. how do your snakes thermoregulate? They won't be able to move to a cooler side.