Maybe research diplexers.
https://en.wikipedia.org/wiki/Diplexer
You can run your satellite signal, AND your comcast signal through the same cable if done properly.
If you have the option - easy mode is to lose the satellite, pay comcast a little more and get your TV and Internet from the same provider during this period. Does comcast even offer internet service in areas where they don't also offer cable TV?
Then, as I mentioned in that other thread where you asked the same question - you just use the existing connector on your camper to bring both signals inside in the same cable, no holes, no weird adapters, or thingies in the window (over winter no less). Just add a splitter at that point and you can run your cable modem off one leg, your TV's off the other.
If you are dead set on having 2 seperate service providers, look into the diplexers or fish a new wire I guess. Sounds like too much effort honestly to go that route.