I also got my IR gun yesterday, they are fun aren't they? What I did was dim the heat pad so that the top of the mulch is 89-91 degrees. When I push some aside and check the glass it's like 105ish. The top of the mulch (well I use coconut chips) is never above 92, and the air temp is usually between 80-82. I would assume that the layer of insulation from the mulch will keep the snake from directly touching the hot glass. I use around a 4 inch layer and tightly pack it to keep it from moving at all. Allowing the top to get to 90 will provide the basking spot needed. As long as your substrate doesn't move and the snake has no chance of touching the glass, I think you're ok.