If you have the spare money(not sure...but I don't think it costs too much..it'd be worth it anyway), measure the bottom of the cage, and go get a piece of glass cut out for the bottom of the tank. Then put some spacers at each corner of the cage to raise the glass up a bit, and all you have to do is put human heat pad(s) under the glass. Keeps the snake from getting directly to the heat pad, and it'd be easier to clean the cage bottom. Just take the piece of glass out and clean.

That's what I'd do anyway. I don't like bulbs much either. They dry the tank too much and I always had to fight with humidity when using my heat lamp for the cool side.