For your heat mat, something that I found helps mine (probe between the mat and the AP cage - there is a pre-cut groove to help the mats lie flat) is to keep a very minimal layer of substrate over it. I found that the surface of the deeper substrate would be 86, but the actual bottom of the cage would be 95, I was having to set the thermostat higher to try and get his surface area where I wanted it, which was too dangerous. Mine has never been a burrower, and flattens his substrate more than moves it, so I just keep a thin layer over it. Just enough to absorb urine, that way I can be sure that if he ever does lay right on the bottom its not going to get too hot. The thermostat is set at 88 and usually the bottom of the cage is 89-91*F depending on the house temps.