"Ethernet Over Power" is one of the technologies being discussed here. It is the same as "Powerline" technology.
There are many "Ethernet Over Power" consumer products available (google will show you some...). I have two of them I bought from Monoprice several years ago. They work pretty well in my home. They can be thought of as "Modems" that convert ethernet to run over the power lines in your house.
I am getting 7.4 Mbits/second on mine right now. Not great but saved me from running cat6 cable to where I needed to put my wireless access point this week for a temporary configuration.
You can't use them on power strips because the power strips do some filtering of the power which reduces or eliminates the signal.
How well they work will depend on the wiring between the two of them. Circuit breakers seem to not be a problem to them.
How well they will work in any given campground can't be known until they are tested. And the results may vary depending on where the endpoints are. And may vary depending on the brand of Ethernet Over Power equipment.
Ed