I don’t know anything about your particular unit, but in the Winnie Class A’s we’ve had previously and in our current one, you can feed the rear TV from any source through the switching box in the front living area – antenna, cable, satellite tuner, DVD and so on. I’d be willing to bet there is a built-in methodology to feed your rear TV from a DirecTV box that is located in the forward part of your coach. If you can’t figure out how to accomplish this by looking at the owner’s manual and your wiring diagram, just experiment - as far as I know, you can’t blow anything up by trying to hook up coax to any input or output designed for coax.
If it was me, I wouldn’t bother.
My problem is that my wife is handicapped, so when she goes on trips with the dogs and me, she rests/sleeps a lot in the back room and she is a very serious satellite TV fan. She also becomes anxious about the driving process and when I am driving she rides in the back, shades closed and watches TV with the in-motion dish. I installed a separate DirecTV box in the back, so that she can tune whatever show she wants without having to come up to the front of the MH each time she wants to change a channel – also, without a separate DirecTV box in the back, all that would be available 24/7 on the front TV when she takes a trip with me would be soap operas, cooking shows, Oprah and the like.
With two separate DirecTV boxes – one front and one back, all of those problems disappear. An extra tuner box for the back TV isn’t expensive to buy and, to my mind anyway, it is worth every penny.