a thermostat for outside temps?? i am not sure i follow. i have an acurite with a probe running to the hot side. the probe is actualy just on top of the substrate. and the acurite is on the cool side. i was going to get a timer so i can have the heat pad turn on at the coolest points, and let the light do the rest. i also want to get some plexiglass to cover up most of the screen, so i can hold in more heat, and humidity.