We have build an outdoor enclosure with two huts what would be the best lighting heat to keep our 4 sulcatas warm thru the winter here in Troy Missouri
Check out the enclosure threads. I believe you will find some heating ideas on there. Radiant heat panels, pig blankets, heat lights. Check the thread out and see what fits you best.
This all depends on the dimensions of your hits and how well insulated they are. Every one is a custom job. All of the ones Barb mentioned are good tools to use, along with a thermostat. Show us whatcha' got and we can make some more specific suggestions.