I don't know what you drive but in our smaller C (24') opening the roof vent in the washroom and running the dash a/c or heat will keep the entire m/h at a good temp. in all but the coldest / hottest temps. The fridge will run for weeks on propane without putting much more than a dent in the fuel levels.
All in all, we find the hour or two it takes to get the m/h, water and fridge to the desired temp once we get plugged in at a c/g or otherwise parked is no big deal.
YMMV (Your Mileage May Vary).
Ted 'n' Laurie, plus Jackson (aka Deputy Dog, the Parson Russell Terrier 'fur kid') and, Rylie (who crossed the Rainbow Bridge June 14, 2012).