Water leak causing delamination.

[TTiffin]

Hello. We bought a used 2009 keystone springdale 249BH fifth wheel. It's in great shape however with all these rain we have discovered a leak. Leaking at a seam at the right rear between the rear corner and the bunkhouse door. Low on the wall in the storage area under the bunks. It's a small area maybe 18" across.
I'm fixing the leak, however this leak has started to cause delamination in an area approximately. 18" across and 24" tall.
So my concern is how can I remedy this so the delamination doesn't keep spreading when the leak is repaired.
And how expensive would it be to just have it professionally repaired, replace the wet sheeting and te fiberglass that small area.
I'll try to get a picture after work.
Thanks, TTiffin

[jdc1]

Here's what I would do after you find the entry point and fix that. Park next to a wall...house, block, tree...anything you can use as a brace point. Drill a small hole or two in the siding. Inject minimal expanding foam. Place a piece of plywood over the entire affected area. Wedge the plywood with 1X's or 2X's, pushing that plywood as flat against the substructure as possible. Leave it for 24 hours. I did it this way on a motorhome 20 years ago. Only side affects were the two 1/4" holes. I wouldn't waste thousands of dollars on repairing it. The way they slap these things together, it's bound to happen again.

[agesilaus]

I'd think about something like this:
Wests leak repair

Lots of YT videos: West system

I'm just guessing that is the right repair kit, you need to call West's and talk to one of their people. Otherwise you can probably add two zeros to the price of that kit to have it done at a fiberglass shop. Just a guess but it won't be cheap.