I think you will find it goes under the trailer given the way the roofs are made if yours is done like ours with the foam that they cut channels in for the a/c ducts. It is far easier to route everything up from under it. I am guessing that there may be an access panel inside that cabinet door beside the stereo unit that you could take out possibly to see where all the wires go. You may even find if you pull the fire place out you will see the cables in that cavity back there.
John & Deb
2011 F250 Lariat FX4 Crew Cab 6.2
2011 Flagstaff V-Lite 30WRLS
Days Camped 2013: 16 2014: 5 2015: 3