What a cute snake! Some TLC is what he needs and by you coming here, it seems like you'll give it to him.
Personally, I would pick up a lamp dimmer from Lowe's and use that on the UTH while the thermoSTAT is being shipped. The UTH plugs into it and you control the power going to it so it controls the heat. Trial and error process. If you're strapped for cash, the 30 dollar thermostat from Hydrofarm on Amazon works. Made for plants, but it'll do it. I'd pick up a Accurite thermometer from Walmart. It has a hydrometer, probe for the hotspot, and inner sensor for ambient temperature. Buying or making hides also. As said, something that is mostly closed. I'd do a plastic sheet from Home Depot and cut it to the top size. Make sure it has air flow. Or just plastic bags, again make sure there is air flow.
And of course, use the advice about blacking three sides and feeding. You could probably even use spray paint on the outside to black it out. Just make sure it is dry and has no fumes when the snake is in it. You can remove spray paint from glass with a razor. I'd give him a week before ejecting him to spray paint his tank though.