Sagging Loft on GS Conquest

Hello all,
I have a 94 Gulfstream Conquest (class C) with a fiberglass body and the loft seems to be sagging, the fiberglass is starting to warp at the 90* between the main body and the loft. My question is how big a fix is this? I haven't torn into it yet, is the main body frame wood or aluminum? I'm thinking maybe broken wood or weld inside the wall causing the sag.

My family and I full time in it and it's been a great rig, but this one thing concerns me. Any answers or suggestions would be great
Sagging Loft on GS Conquest

Could be a big deal. Cost a friend of mine over $1500 to get it fixed. Was a structural failure requiring removal of the fiberglass and repair of the frame. Scout around until you find somebody who seems to know what they are doing before getting it repaired. Good luck :(