1999 Rockwood Ultralight Roof Repair

I am in need of a little guidance on the roof repair on my 99 Rockwood Ultralight.  I noticed I had some water damage on the roof and the ceiling of the camper and decided I need to start with taking the rubber roof off to assess the damage.  I have successfully removed the rubber roof and see that every section of the luan had water damage.  What surprised me was the fact that I did not see any rafters or support beams as I have seen in most videos and blogs referencing RV roof repair.  I am going to take the ceiling out too since some of it is drooping as well.  From what I can tell, I will have to take the cabinets out to accomplish this as well.  Anyway, here are my questions:

1. The luan on the roof appears to be clued to a 2inch thing piece of foam insulation.  I have tried to scrape the luan off and while the rotten material comes off easy the luan which is still good is not that easy to get off.  I am afraid the foam is saturated with water after seeing the extensive damage to the original luan.  Should I be replacing the foam and the luan?  If so, where is the best place to find this type of foam.  If I can reuse the foam, any tips on removing the glued down luan.

2. As mentioned, I am going to have to replace the ceiling panel material as well, I wont know until I get the ceiling panels off but another post I read said there will probably only be a couple metal support beams located in the front, middle, and rear of the camper.  Does this sound right?  The ceiling does feel extremely week to the point you think you might fall through in certain places.

3.  If there is only a couple support beams for the roof, would it be easiest to take the foam completely out, buy replacement foam and glue the luan to the top and the ceiling panel material to the bottom prior to putting the foam back in?

Any information will be greatly appreciated.  I will post pictures shortly.

Gary

Update:
I have removed the rubber roof and discovered there is no support rafters in the camper, just a 1 1/2 inch thick piece of foam insualtion with Luan glued to the top.  I also gained access to the ceiling after removing a couple cabinets.  Again no support rafters just the ceiling sheet glued to the underside of the foam insulation.

Best I can tell, there is a 1 1/2 x 1 1/2 aluminum frame going all the way around the top of the camper (See Pictures).  The ceiling sheet seems to sandwich between the aforementioned aluminum frame and another aluminum frame under it.  I can not see how these aluminum frames are joined together other then being welded in the corners.

So now my delima is how do I get a new roof on without any support rafters to attach things through when I can not get anything back between the 2 aluminum pieces.  The way I see it, my only option is to TIG weld some aluminum support rafters or simply put in some type of wood rafter.  One problem I see with this is that I only have 1 1/2 inches to work with to put the ceiling, insulation, and the rubber roof back on. 

Any suggestions.

Unusual - there typically will be at least a few cross-members. sometimes as much as 4 ft apart.

Can you slide in some 1x2 cross members? Standard 1x2 is 1.5" thick, so ought to fit in that slot between the two aluminum outer frames. Cut them to length, hold at an angle to fit one end into the slot, and then force the other end in until it is square. Drive a screw in each end to keep them in place. Then lay a plywood skin over that. You don't need a lot of cross members.

You could probably do the same with 1.5" aluminum angle or box tubing. And maybe lock them in place with pop-rivets.

Gary,
Thanks for the input.  I have not moved towards the back of the camper yet so there may be some support around the A/C unit and then further in the back next to the master bed but I don't want to rip the ceiling completely out until I have everything in place to put it back together. 

Since I am having to replace the entire ceiling, will I need to remove all the cabinets to slide the new ceiling sheets in place?  If I replace the current foam insulation with foam board, what R value should I look at using?  I don't know where I would get the 1 1/2 inch foam board to put back in so I am looking at the new foam board like Lowes carries.  I would think if I am putting plywood on top (which was not there to begin with) I would not need as thick a piece of insulation.

Gary