Thanks for all the replies.
I don't have and don't have the money to buy another thermostat. I've just heard of people using the dimmer and when their T-stat failed, it saved their snakes.
I can see and understand the issue with using the dimmer from what Kitedemon said, and I can see it only getting too cool at night.(can't make the temp higher at night, but my room temps in the day are about 80 and only because my lizard has his heat lamp and stuff)
Anyway, thanks for all the replies!