Your DVD output to your main TV is through a Coax?? Must not be HD.
Anyway, I had a Keystone Montana and was able to ouput to all the TVs by using the Coax output and attaching to one of those barrel connectors currently looped together. I later changed it back and just got small DVD players for the other TVs that connect direct.
2008 Ford F350 2014 Redwood 36RL -
Our Rig Onan 5500, Splendide Ariston W/D, 8K axles, disk brakes, G614s, tri-glide pin box,
6-pt leveling, dual heat pump, dual awnings, Trav'ler SK-1000 Dish