Are we speaking of the thermometer or thermostat probe? I also keep substrate to a minimum over the hot spot There is no burrowing possible basically just enough to suck up pee if there is any. There is lots of variations. Temps are odd people speak of surface temps and ambient temps.
I take surface temps from the floor inside the warm (hot) hide and surface temps inside the cool hide. Ambient air temps are the temperature of the air circulating inside the enclosure. 79-85 range is fine. Young snakes don't need as much heat as older ones so they can run on the cooler side and really old snakes on the warmer end the rest in the middle.
One point to remember is ambient temps cannot be taken with a gun thermometer it simply cannot measure the air. You need some other type, they also do not do well with very reflective objects either. In my case that makes them suspect for measuring the hot side as bits of plastic or glass poke through the substrate and it is simply too shiny to be reliable.