Yep, I have some really bad new for you...
Having traveled as a fulltimer around the US, the majority of campgrounds now offer fairly strong wifi signals - most accessible from the built in WiFi antennas on laptops - occasionally needing a small booster antenna.
Unfortunately most of them just allow 'free for all' access resulting in almost zero bandwidth when everycomes gets back from the beach, shopping, sightseeing etc.
Having the strongest WiFi signal in the world won't help you then.
Occasionally I have come across a campground that has woken up to the problem and implemented bandwidth shaping, banning peer to peer etc to make it accessible to everyone.
As I need WiFi for work, I have an AT&T hotspot and Millenicom (Sprint) unlimited hotspot as well as the CG WiFi.