They have a compressor if it gets as cold as indicated, looks like draw is below 50AH a day, you could feasible get 3 days from a pair of batteries. I think 4 days would be pushing it and harmful to batteries, a solar suitcase can easily be deployed to help keep up with demand.
When off the grid we have solar, a fast charging converter, and most importantly, for true self-containment, we have both Onan and portable Champion inverter gennies. We figure why take a chance, we can camp anywhere, anytime, and under extreme weather conditions.
