Nope I haven't as Clorique says (for the reasons posted) it isn't recommended and voids your warranty.
How can they warranty anything that you basically have to manufacture yourself? I didn't even know they offered a warranty.

Becky, I notice that you're heating the entire tub instead of only 1/3 to 1/2 like is usually seen. How is that working out for you? How do your snakes get cool if they need to? Do you have some vertical space so they can climb? And what is your reason for putting the 11" and the 4" right next to each other? Are they controlled by different thermostats? Do you have warm and warmer zones instead of cool and warm?

Mark