Glenn, the one I worked on had a very saggy roof over the dinette. In fact that whole wall had settled a bit. Without lots of trouble and effort, and possibly no good resultant, I decided to leave the lower part as is because it looked fine for the most part anyway, and just raise the upper part of the dinette cupboards and roof a couple inches.
I braced from the frame up to the cabinets, slowly lifting them over a couple weeks. I then had supports manufactured that sat on the frame, and supported the roof. I am very confident there will be no more movement in the future.
I know you all have seen this before, but here is the end result of what I came up with.
Here is where it attached to the lower part of the dinette.
At that point I bolted through the fibreglass wall on the dinette directly to another support that sits directly on the frame. This support is hidden inside the dinette shell.
Here is what I did at the ceiling to spread the support out a ways. This support is connected to the upper cabinets for stability. This support holds both the moulding of the cabinets, as well as the roof.