I'll answer from my experience. I have a Tracvision mounted on the roof and it has two cables that come into the compartment over the drivers seat where the switch box and dvd player are.
When I use my portable dish, I run the cable through the window and attach to the back of the switch box. Mine will not work if I hook it to the "park cable" box in the "plumbing bay".
I hope this is of some help.
Jim with Judy
2017 Newmar Ventana 4369, 2005 Jeep Wrangler (Rock Crawler), 2016 Jeep Wrangler (Mall Crawler)