I was about to purchase a reptitherm heating pad, but then decided to double check before I bought it and look into radiant heat panels. I live in Florida, and just want to be prepared for the cold snaps and a few hours on the nights that dip below 70. I'm not sure which product would be the best for my needs. Also, does the heat pad just sit on top of the substrate? I know the further buried down the heat mat is, the hotter the actual mat, and I don't want to risk burning my tortoise. Forgive me if I sound naive; this is Bowsers first "winter" outdoors.