WiFi Extender

Sitting in a motorhome and receiving WiFi on a ver low level since the motorhome is like a Farady cage. Using a WiFi-Repeater is not possible since I have no access to the WiFi-modem which belongs to the campground owner. My idea is having a WiFi-Receiver outside the motorhome where the signal is strong enough and transfer the incoming signal from the original channel to another channel. This way I would have a strong level inside.