If it's the Furrion system like ours, you can get their router and service. It's quite expensive.
https://furrion.com/pages/access
I already have an AT&T unlimited plan with a 4g router, so I tapped into the antenna and hooked my Netgear router to it. It has pretty good reception, compared to just using the router's internal antenna. I ended up using the 12v power available there also and put in a USB plug that I can use to charge my router. Mine is on the wall, so I used command strips to mount it near the Furrion connector, then got 2 SMA to T9 connectors (
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1) to plug into my router's antenna ports.
Here's the USB plug I installed...
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1