not enough heat in the back
Jammer, I don't know if your question has been fully answered since I didn't read all the comments, but here is what I did on my 2004 Classic 30 footer.
In order to cut down on the turbulence inside the ducts I stretched and straightened out the ducts as much as I could. I then wrapped most of them with reflective 1/2 inch insulation, while keeping them as close as possible to each other to minimize heat loss.
In the bedroom I opened the vent and slid a aluminum tube that just fit INSIDE the ductwork as far as I could. This cut down on the turbulance, gave a straighter flow of the air and has increased the temperature in the bedroom noticeably. Wolf146