My snake room when power goes out will be heated to 88F with a propane heater if needed. The generator is there for keeping racks heated. The rodents wont enjoy the heat at all but they can be replaced easier than the snakes/eggs.
If you can keep room at 88F just open incubator door to allow it to even out and your all set.
I use a coleman catalytic indoor propane heater with the room window cracked 1" to keep fresh air circulating. one 16oz can on low keeps room at 85F for 8 hours, On high itll hit about 89-90 if door stays closed for 4 hours. You can also get the hose kit and hook it up to a full size propane tank and be set for a full 3 days. Of course one small propane heater wont help in dead of winter, so this is where the generator comes in to power the radiator heater on Med setting(750watts) and then the propane heater is kept on low.