I'm unclear - why are you doing this despite it being a bad idea? Is it because it's a cheap way? If so, how can having 2 sick snakes and 2 vet bills be cheaper? If you want to go the cheap route, how about setting up a rubbermaid? Less than 10 bucks for the tub, add a heating pad, use paper towels and butter tubs or flower pot bases for hides. Could easily spend less than $30 bucks on this setup.

I know, not what you probably wanted to hear, but it's another cheap alternative w/o risking the health and comfort of your snakes.