I bought an 05 990 in 2011 or 2012, I've forgotten when. It had leaks in several locations. I planned to repair all the issues "next winter".
I did maintenance and stopped all the leaks. I repaired the rotten areas under the battery box and gas compartment. I also replaced the bottom cover under the basement.
I never got around to repairing the front cap. After stopping all the leaks we have used it year after year. The skin of the front cap and beneath the bed is backed only by card board. Once it dried it still had a few waves/ripples in it but wasn't rotten and it hasn't fallen apart.
The only thing that I had to do was get the musty/rotten wood smell out, which turned out to be the two spots of rot on the wings. I think that would have dried too but I had no choice, the wife said so.
You need to stop the leaks first. No silicon. I use Dicor but any of the usual camper sealers will work.
On my AF, the front cap leaks were the clearance lights.
If you are handy with repairs, you can repair it to better than factory, but it does take a little work. In 2010 I replaced the roof and front cap on one with my wife's help. It took us 3 months of week ends.
There were a lot of examples on RV.net but they may no longer be available as we've lost photo storage servers. I'm sure if you ask specific questions someone can help.
I forgot to mention, 100% of the info you get on this web site is opinion, including mine, so read up on what you need to fix before drilling and cutting. One opinion rather than another may be better for your particular need. Once you've taken a particular route it may be hard to recover.
