No, don't use hand warmers from walmart, thats asking for trouble. Use the heat packs people use when shipping. They have a maximum temp of like only 100degrees or so. They peak there for a certain number of hours too. Hand warmers are much more unregulated and could cause a problem. I would bag the snakes up to move them. Don't put the heat packs in the bags with them, just in the box or plastic tub they're being transported in.