From your description sounds like you keep the unit in a stationary position on a regular basis maybe hunting spot or permanent/seasonal lot. You're upside down on your financing and trying to retain some value.
Were this me, I'd start by stopping the leaks first since in time it'll only extend to the bunk ends as well. A seal test or perhaps dyed water sprayed onto the unit will help you to discern the source of leaks.
Then begin to repair the leaks and discard and rebuild any areas that have become water-logged.
No idea how to repair delamination but at least you won't be worrying about where to place water buckets.
I suspect the subfloor is going to need replacing at least in the area that hold the entrance step. Go ahead and insulate/caulk to avoid rodents at the same time since you've already easy access.
HTH.
