You CAN use a dimmer on the UTH, it is not the best choice though.
Hydrofarms are pretty cheap I've paid more than $30 for a light dimmer in my room so I don't see much sense in going for a 2nd best option when there really is only a minimal savings.
But, if the room the snake is in can be kept at a very constant temp then a dimmer can work. If the ambient temp in the room swings the dimmer won't help keep the hot spot at the same temp.
What I would use a dimmer for, is to tone down the heat output of say 150 farm grade infrared bulbs. And, that would still be on a thermostat. The reason I would do this is 150W farm infrared bulb is about $10 here while the exoterra 75W infrared bulb is $17 almost $18. Also, running a higher rated bulb in a constant or near constant "on" cycle should contribute to longer bulb life.
I don't know if there is much to be gained from doing this with CHE's which to my understanding already have a very good service life.
And, you might want to start saving for something bigger than a 10 gallon or researching tubs/racks or terrarium/vivarium builds.