electricity at the campsite

You can look up campgrounds online and see the cost for a campsite with and without electricity; per day. The long and short of it, all things considered, it will never be cheaper to use a generator or any other “power source” then to get a “site with electricity”. The one caveat being, if you are real stingy with power you may get up to 3 days be running off the battery. But that would mean no microwave, no air conditioner, and a marked increase in propane use and a marked loss of battery longevity. After the 3 days your camping trip is over and you would need to go back home and charge up the battery - wash and repeat.