Well we've completed a pretty darn quick repair of the sagging roof and I will include a few pics.I would be happy to send more later if you like.
We started out by removing the old AC unit as we decided we won't be using it for the time of year and places that we travel.(By the way it works well and we will be selling it off.We will be heading from Santa Barbara down to San Diego between Jan. 22 and mid Feb. in case you're interested).
We had been given various advice whether to repair the sagging or not, but my friend is a bit of a madman and has done boat repair so we decided to try and recrown the roof.
After removing the AC unit we cut a 3 inch strip thru the inner ceiling board to expose the layer of foam between it and the fiberglass
skin.We then removed all this foam and were left with a 3 inch channel with just the exposed fiberglass
skin showing.This was done at a joint in the roof board panels close to where the roof was sagging most.Our main intention was to recrown as much as possible so that any water would flow off.There was also an issue with the fiberglass
skin delaminating and rippling so we addressed this as best we could as well.(Info later)
We had removed the cabinet doors for access and to see what was going on in there, and came to the realization that the roof on these units is supported by the cabinet structures and has no ribs for support.We decided to put one support rib in this cut out by using two 1X3 fir boards glued together (my friend had worked on boats as mentioned and knew that by gluing two pieces like this together, that they retain the curve in which they are glued).
By gluing the two 1X3 boards and using 2x4 boards of varying length, tall in the middle and shorter on the outsides we created the amount of crowning that we wished.From the photos you may see that we used what is actually a motorcycle jack to push the roof up to make the crown a little more so when we took the boards away the crown would settle back just a bit.
We also took fir 1x3 and put a notch through the kitchen counter and put these support beams perpendicular to the cabinets to push the sagging cabinets up and provide more support to the roof.
The roof recrowning and support of the cabinets worked quite well with the roof having virtually no sag in it and certainly no longer a bird bath up there.
The rippling and delaminating repair we tried met with mixed success.There was little rippling left but still some delamination or separation of the fiberglass skin from the foam layer below it from the sagging.We drilled small holes in the roof where the obvious delamination was and tried to fix this by putting expanding foam in there. Definitely a bit of a warning on this, in that it worked a few places but in other places on the roof it actually made the roof sag from the inside....OOPS!I think this could still be done this way but would require pushing the roof up from the inside in the same way we did when we recrowned.
Anyways, things are certainly much better and do let me know if you have any questions, I hope this helps.
ps sad update; I'm trying to attach the photos but am unable to I'll try later.....