A small back up generator just for your heat lights is a good thing to have and they are fairly cheap now a days. A propane heater would work but you would have to open a window which would make the humidity drop, Also I another idea is a foam dissposable cooler and smaller tupperwares for the snakes and hand warmers. Poke holes in the lid for some air. tape the heater to the lid to keep the heater a ways away from the snakes. One other option is buy a snake shipping package from "weshipreptiles" a 12 hour to a overnight shipping package with their heaters should keep the snakes cozy till the power return. I hope one of these ideas has helped