This was a multi part process.
Here is what it looked like after I removed the window.
http://i810.photobucket.com/albums/zz29/skyking60/delamination/delam004.jpg
Water may have entered here at the back corner of the window to get it started.
http://i810.photobucket.com/albums/zz29/skyking60/delamination/delam007.jpg
I applied tape over the panel, to keep from marring the paint. This give you an idea of the size, approximately 1' by 2' More on that later.
http://i810.photobucket.com/albums/zz29/skyking60/delamination/delam009.jpg
My first attempt, I used a tube made from a few air nozzles and a syringe, and injected System Three Clear Coat epoxy. I have several products to choose from, and picked the clear coat because of lower viscosity.
http://i810.photobucket.com/albums/zz29/skyking60/delamination/delam011.jpg
I injected the epoxy down between the luan plys , FRP, and foam core in the window edge area.
http://i810.photobucket.com/albums/zz29/skyking60/delamination/delam014.jpg
I stood up a 4x10 that I had, clamped it above and below the window, and used wood and wedges to drive the delam back in contact.
http://i810.photobucket.com/albums/zz29/skyking60/delamination/delam017.jpg
http://i810.photobucket.com/albums/zz29/skyking60/delamination/delam015.jpg
I tented it over and kept it warm for 4 days. The clear coat is some very slow curing resin.
The results? I got a partial repair. The edge of the window was solid down about 4 ", but below that there was still a bubble; you can push on a slight delam like this and feel it.
I chose the System Three silvertip laminating resin and fast hardener for the next go. Now the edge was all glued up and I had no access to the bubble. I got out my telecom long bit and did some surgery.
http://i810.photobucket.com/albums/zz29/skyking60/delamination/delam01.jpg
I measured out and drilled a couple of holes from above, down through the foam core at an angle to access the delam bubble. I felt the FRP skin and could feel the bit on the other side. I had to chew on that luan plywood to be sure i got epoxy past it, but not clear through the FRP.
http://i810.photobucket.com/albums/zz29/skyking60/delamination/delam03.jpg
I used 1/4" tubing to get the resin down to the repair.
I used the same 4x10 and wedges, but left some gaps so I could monitor how I was doing. The failure on the first attempt was due to not getting resin in there, and also not getting the surface clamped properly. I could not see this with the wood and wedges on the first go.
http://i810.photobucket.com/albums/zz29/skyking60/delamination/delam08.jpg
The results; a repaired delam without any refinishing of the skin of the trailer.
http://i810.photobucket.com/albums/zz29/skyking60/delamination/delam19.jpg
http://i810.photobucket.com/albums/zz29/skyking60/delamination/delam29.jpg
I filled the holes with silicone to prevent any moisture getting in.
http://i810.photobucket.com/albums/zz29/skyking60/delamination/delam17.jpg
Removed the old foam seal from the window and used the adhesive putty.
http://i810.photobucket.com/albums/zz29/skyking60/delamination/delam21.jpg
http://i810.photobucket.com/albums/zz29/skyking60/delamination/delam30.jpg
Window is back in, waiting for all the excess putty to squeeze out, and then caulk with silicone.