and you probably already know this, just wanted to make sure. If you bag the snakes up and use your body heat to keep them warm, remember to put each one into a separate bag. You can use pillowcases as snake bags if necessary, just make sure that the top is tied securely without tying the snake's tail or head in the knot.
I also have heard of people using this trick and climbing into their bed and covering up with lots of blankets and comforters.
Or you can invest in some of those little disposable $1 hand warmers and use them as emergency heat pads under their tanks. If you had one, I would use the small plastic critter keeper shoeboxes to conserve heat with this trick. I think you can buy big boxes of them at the super warehouse stores sometimes.
-----
sue