Just buy a genset instead of the whole motor home. A genset is what's going to be running in your motor home all night to power an AC.

Honda small quiet genset

900W rated (7.5A)
Fuel Tank Capacity: 0.6 gallons
Run Time on One Tankful: 3.8 hrs. @ rated
load--8.3 hrs. @ 1/4 load
Dimensions (L x W x H): 17.7" x 9.4" x 15.0"
Noise Level: 59 dB @ rated load
53 dB @ 1/4 load
Dry Weight: 29 lbs

So this one doesn't have a big enough tank to run all night, but it has more than enough output for the AC.
The next size up would probably have enough fuel and would run quieter since it would be running at a lower load level.

John Courter
Don't work for Honda, just want one.