But why not just get a thermostat and keep the UTH at a safe temperature? they really aren't that expensive... say the average BP lives 20 years... Say you get a good thermostat... the herpstat 1 (retails for $139.00) that means that over the life of the snake, does $139 really matter? that is $6.95 a year.
And a proportional thermostat will increase the lifespan of a UTH. UTH's are basically giant resistors. The number 1 cause of premature failure of resistors is overheating... just like almost every other electrical component.