The cable tester is where I would begin. You can also use a multi-meter if you are not sure how the cable tester works. Start with the Batwing as you will want OTA TV no matter what else you do. Inside the coach you will be looking for a wall plate with a tiny button or switch with a light that turns on and off as you push/slide it. This is the power supply for the Batwing antenna. There will be connections on the back for ANT, Cable and out to TV. There may also be a TV output on the front face. Get up on the roof and disconnect the coax from the Batwing. With a multimeter check to see if you are getting 12VDC by touching the center conductor and the outside collar with the probes. If not, you can connect the tester or short out the coax with a bit of foil. Go inside and find the other end of the coax and connect it to the wall plate that says antenna. You can do the same thing for the coax that comes from the cable connection (except there's no 12V, just trace the cable). The wall plate then becomes an A/B switch so you can choose to watch Cable or OTA TV with the push of a button.
The Out to TV on that wall plate should then give you a coax output to a splitter with one coax going to the TV close to the wall plate and the 2nd coax going to the 2nd TV which you might have to "tone" (trace) as well.
Good place to start and we can move on from there once you get that completed. It's not a hard job, it just takes a bit of time and patience.
