heating questions regarding thermostat.

[revent]

So I have three snake enclosures two exo terras and a 20 gallon long and my girlfriend wants to get her own ball python at the next reptile expo so a fourth enclosure is on the way. I am relatively new to reptiles and so far I have my setups using an UTH and a light and just use light wattage and distance from cage and thickness of substrate to get my temps right in my enclosures. It seems to be working I feel like my snakes are all happy and healthy I keep an eye on them closely when the weather changes I adjust there setups slightly and they have lower watt bulbs for night.

This is starting to get complicated and I think I want to get rid of the light bulbs for heat and just use either radiant heat panels or maybe a second under tank heater, and make some custom acrylic tops to keep heat and humidity in some cases in. So I definatly need some thermostats, but with a thermostat How do you lower your temps for night? Do people just leave there snakes at the same temp all the time? What kind of thermostat should I get, I am on a budget. Any other thoughts or suggestions?