I have a UTH brand that says it doesn't get too hot. Don't believe the literature that comes with these. I've measured 110F on the glass with this UTH unregulated.
A t-stat really is a must have. Some of the older literature will say that the t-stat is not necessary for colubrids, because unlike some other popular pet snakes, the colubrid will leave a spot that is too hot. I don't agree with this logic, however. The pet is stuck in a cage, and shouldn't have to choose between one space that is dangerously hot (and the warm hide may be too hot over an unregulated UTH, even if the snake can get some insulation on top of the bedding in there), and a space that is too cold. We should make the effort to get the temp just right.
Sometimes easier said than done; I know.