3500 miles with class B hybrid (FLA and Li)
Phoenix, Boise, Spokane, Portland, San Simeon, CA, Phoenix.
Bottom line: 100AH Li and 80AH FLA with a DC to DC charger will support a compressor cooler and furnace in freezing conditions without use of a generator.
Probably do as well with a compressor refrigerator.
Cooler run by the FLA, everything else by the Li. Cooler overnight about 20AH, furnace about the same. Li back to 100% with less than an hour of driving. FLA charged by the end of the day but if not could be charged by the Li.
Engine idle charges Li at 40 amps.
Two sessions of driveway shore power used .3-.8 amps of 120 volt power. All other camping done without shore power. Both batteries at 100% at sunset.
You can support a compressor refrigerator with the addition of 100AH of Li battery and a DC to DC charger. Generator not required.