I read an interesting stat sometime back.
It takes 1000lbs if LiOn battery to equal 1.85 gallons of gasoline. If your Generator is only 20% efficient you can save a bundle and save more by not having ti haul around a ton or more of batteries.
I don’t think it would be a ton unless I tried to stick with lead, probably less than half that. The furnace can go, the unit heats as well as cools. Couple of other things can be done to compensate, smaller propane tank, etc.