You may want to check out some of the members and their units at our
Wi-Fi Signal Extenders . The unit you are looking for is one that has an EXTERNAL antenna. The antenna needs to be mounted above any surrounding obstacles, such as RV's parked next to you or in between you and the CG's AP.
There are many different types available.
I use the EnGenius ENS202EXT model (used for commercial use mostly) and have had GREAT results with it. The last price I saw was $79 on Amazon (new). I have had signals that were 1.5 miles away.
One thing to understand is that it will do a GREAT job of increasing the xmit/receive signal between you and the AP, but if there are 10, 20 other campers connecting to the same AP, your signal will be great but you are splitting the MAX data at the AP with 10 or 20 others, so it will still be slow.
Don
My Registry
RVing with SOLAR