If I'm understanding you correctly:
1) Your cable-in on the exterior of your coach DOES work correctly (i.e., if you hooked up to park cable, you'd get the signal to all of your tv's).
2) This doesn't seem to work for your Dish Playmaker. You want to take the video out from the Playmaker and distribute it to all of your tv's.
If #1 is true, then you already have a splitter somewhere in your coach that takes that single feed in and distributes to all tv's.
If #2 is also true, what you need to do is figure out WHERE that splitter is in your coach. (They put those in crazy locations; mine is behind the built-in dresser drawers, where you would never think to look!) Once you find it, take your video out from your Dish Playmaker and run it to the input side of that splitter.
Our rig does exactly what you want yours to do, but it is a 2020, so that is probably why there is a little easier solution on mine than what I just gave you, but this one won't cost you hardly any money!
Good luck.
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