Add a
solar panel. I put one 100w panel on, and can go over a week (that's as long as we have boondocked, so far) and not worry about power. Fridge, heater at night, all lights LED and no conservation of power enforced.
Between trips, I have a hole in my TT cover, to allow the solar to keep my battery charged (one Group 27, 105 Ah). Solar is the best addition I have done, as I don't have to worry about power, even when winter camping. I have it mounted flat on my roof, and it recharges completely during the day, in November. Heater cycles all night.
Again, solar. Rest easy.