I have two questions, first is do you have the "box of many buttons" that the connection from the park cable goes to? The second is are you talking DVD only with no interest in BluRay?
If your answer is DVD then I have a third question, is the DVD player connected to the "BOMB"? If it is, your already connected. If not and your player has an RV out connector, hook it up to the BOMB. If it is HDMI output only you will either have to buy a little HDMI to RV converter to use the existing cable and the BOMB.
If you don't want to have the converter and you want to play BluRay disc's, run a HDMI cable however you want to the rear TV and buy a HDMI splitter so you have two HDMI outputs. Most DVD and BluRay players only have one output.
The easy way out is buy another BluRay player.
My family wanted to be able to view the same movie on both of our sets and I went for the splitter and 45 foot cable run under and through the RV.
All the equipment is available on line at reasonable costs. You can search for my posts regarding the running of the cable and the installation of the HDMI cable.