If the issue is that the campground doesn't have enough bandwidth to support its guests- no amount of boosting will fix that.
To test- go to where the WIFI is the strongest with your phone/laptop/whatever device. Try completing whatever activity you're attempting to accomplish from there.
If it's good there but not your rig, a booster will help.
If it's not good there, a booster won't help.
I have a WiFiRanger that is an EXCELLENT wifi booster but I almost never bother with campground wifi. I use it as a network backbone and as a method for switching all of my devices from one internet source to another.
For Internet, I carry unlimited data plans on both Verizon and AT&T.
See if this article helps:
Cellular, wifi, and networks – OH MY! | Learn To RV