Do you have thermostats running the CHE and UTH? If so: where are the probes positioned?
Any which way-you could simply put a towel draped over the top of the cage on the cold side (to prevent the heat from the CHE escaping through the screen top). Or you could get fancy and actually cut some insulation board and tape it to the outside of the cold side of the enclosure: https://www.homedepot.com/p/Project-...-PP1/203553730 you would get the added benefit that obscuring visibility on part of the enclosure would add a sense of security for the snake by making it less 'exposed' in an open area.