Powerline equipment uses the actual power lines to send the signal. Imagine it as a dedicated Ethernet cable running throughout your home and you can plus a sender in at one location and it can be received at multiple other locations on the same set of circuits. It's certainly not snake oil and it's not any kind of an amplifier. It will be interesting to see how this could be implemented in a campground but sending the signal through a separate 20amp circuit that goes to all sites just might work! I am not sure how anyone here knows what the backhaul is at this location. Powerline equipment will not improve the backhaul but a better connection (powerline vs. Wifi) could easily improve the end user experience.
I am interested to hear more.