Internet RV is 300 feet from home -- WIFI /??/

Ubiquiti.. Google Nanostation Loco M

This is what I call a "Wi-Fi Modem" in that it is a Wi-Fi Client (or access point it operates both ways) with a LAN port (Plug in your cat 5) to whatever you have inside the RV. 300 feet is nothing over open ground to the Nano Staion.

3 MILES over open ground (No trees or hills or buildings) is doable.