Greetings!
Adapters are always good, I have 20, 30, & 50 amp adapters. They take up very little space, and it is best to be prepared. Also pick up an electrical connection tester, many of the outlets at campgrounds are wired wrong, and can cause you lots of problems. That’s just one of the reasons why I rarely use them.
I can go 2 full weeks on battery power alone, and that includes running my air conditioner (swamp cooler) full time. Another trick is to add an inverter close to your starting battery, then run an extension cord back to your trailer, so you can plug a battery charger in to charge your trailer’s batteries while you drive. AC can have a smaller line, and not suffer the losses that running 12v that far would.
Cheers!
"Be creative & recycle, reuse, & repurpose." ~ The Camper Van Man