That's crazy. I thought all RVs had a cable input in the water bay or power bay.
And I run my sat in through mine on every RV I have ever had. You just need to make sure there are no splitters or amps between the cable and the sat box.
One RV didn't have room for a sat box where the cable came out so I ran a new one.
I bought a 50 cable, found a hole in the firewall behind the dash and ran it up a corner pillar to the sat box and coiled up the excess in the front engine compartment.
Open the hood and bring the cable out. Usually long enough to reach the sat dish.