I've started to think about this too, I only got my first herp last month so never really worried about my fish tanks. Now that I'm (almost) nearing the end of having everything dialed in temp wise after some trial and error. Wondering about a power outage. Like you I live in a cold climate, last year we had an ice storm that took out power to some people for over a week. Where I lived at the time was only 12hrs but I've since moved. I only have 2 snakes and rent a basement apartment so I'm limited on a dedicated room or modifying things.
Has anyone tried using booster packs for your car with the built AC adaptor to run a cage or 2?