On rentals weíve always been charged for generator use on an hourly basis. For the most part weíve only used generator to power microwave for a few minutes during the day, so it hasnít added up to much cost ó certainly negligible compared to rental costs and gasoline.
The only time I recall running generator for A/C while driving was while climbing out of Death Valley eastbound when old motorhome started to struggle a bit and started to overheat a little. I turned off dash A/C to help engine a tiny bit, so ran the generator and roof air conditioner for maybe an hour.
With Cruise America rentals if you run the generator all the time while driving, it could add up. On a 5,000 mile trip you could see about 100 hours or more of generator charges. I donít recall hourly charge but itís significant.