I have colubrids and carpets in AP cages which also have a place for the thermostat probe. I use the ultratherm UTH's for belly heat. I also use IR bulbs or CHE's to boost my ambient temps in the colder months. I like the ultratherms because even without a thermostat they don't get too hot. All of my UTH's have thermostats attached to them.

http://www.reptilebasics.com/ultratherm-heat-pads