I plan on going with a generator if hookup power is unavailable, but as said, I have learned to be "paranoid" over the years. I have backups to backups of my backups, so I plan on getting batteries and a larger inverter if needed as a "last resort".
The RV is used, and being prepped now. i should get it next week. The original owner added a lot of "extras" or "optional" items, so I'll have to check the inverter size when we receive it.
There is plenty of storage underneath, but reinforcing it for extra batteries is a good idea. Better safe than sorry.
If the continuous oxygen concentrator is "too much" for full time, we could get some extra batteries for her portable oxygen concentrator. They run about $400 each, and last for 8 hrs (+ or -). It takes 120V 2A to charge one of those, but you could have enough of them to run the portable during the day, then recharge at a camp overnight. The continuous stationary might then run for only 8 hrs when she is asleep in bed.
I have even thought about getting one of those small portable generators used in camping as a generator "backup" just for the oxygen.
Keep posting any thoughts or suggestions.