Hi,
Remember if you put a UTH on the cool side you can control it with connecting it to a dimmer switch then connecting that to your thermostat that is controling the warm side - you will want to monitor and adjust it fairly often at first till you get the dimmer set right though. This is probably best done with the snake not in the enclosure - another reason to have the tanks set up and stable for a couple fo days to a week before getting the animal wherever possible.
It can be trickier to set up than two thermostats and is obviously a compromise but it should be possible to do it.
dr del