I used to have a battery, inverter, and small
generator combo with my old
Casita. The one I have now has the overhead AC and running it from a battery/inverter setup is a lost cause.
I had 2 golf cart batteries, 2500 watt inverter. It would run the 5000 BTU air conditioner through the nite until 7 AM so I could get a good night's sleep.
Would have needed a really large
solar panel to recharge the batteries during the day. Didn't need AC daytime since I was working or in the water.
This was in South Texas where from May to Sept. you at least need AC to sleep. When awake you can float in the river, sit in the shade, etc.
Looks like I need to go to Maine or Colorado in July & August. In CO those months you will see about as many TX
license plates as local.