I doubt you will find that "every" campground requires 3 night stays. I enjoy staying at Wal-Mart's and truck stops when I am just trying to get from point A to point B, but I have lots of batteries and a large inverter so I only have to run the generator in the evening while cooking and a bit more and then a bit in the morning before we leave. The drive will charge us back up again.
Are you going to need A/C all night in July? If so, you may end up running the generator 10-15 hours but that's still likely not too much more than it would have cost to stay at a campground.
Either way you will be OK, it's just a matter of what you want to do and where you want to do it.