Leah,
The factory cabling from the DVD and satellite hardware location is coax to the center TV! The HD cabling is going to the small TV over the windshield. I believe this is a common mistake by many coach builders. The DVD and Satellite receiver needs to be located near the large center TV. There's a great shelf above the TV that would be perfect. Not only does this fix the HD problem, but it gets the electronics out of the original location that's not really large enough for the equipment. I can make it work with the coax that's there to move the satellite receiver. The only issue then is that I wouldn't be able to view satellite channels or the DVD on the front TV. If I have to go down that path I'll install a small DVD only up front for the small TV and it will be restricted to DVD or over the air TV. Maybe, that's my best approach.
Gil