Thermostat probe stays outside then, right where it is! I don't know if I can make a probe sandwich because these reptitherms say not to remove after sticking it on there, so I might have to play around with that thermostat then. I will move the bulb and remeasure when I get home today- and measure the glass directly. The heat gun is one of the best tools, I swear by it. Do you guys have a good reccomendation for different thermometers for each side though? My thermometers probes are inside above the substrate, should they go on the outside on the bottom of the tank instead? They are just measuring the air above the substrate right now.

Also, would a separate thermostat be better for the lamp? Instead of a rheostat? I heard that rheostats can be a pain to control, and our house changes temperatures pretty frequently. How would you set that up if so?

And I don't think there's too much substrate- I just used one brick of the coco husk after putting it in water. It doesn't even fully cover the tip of my finger, but enough so you can't see the glass. I would say .5 inch or less. And thanks for the concern on the tank size- this guy is about 3.5/4 feet so we might be upgrading to a larger size.

I included a picture of my setup now in case a visual helps! This is sans the lamp, which is currently placed on the warm side(side the cat isn't on), but I will be moving it over.