I inherited this trailer from a relative recently. They had bought it used in 2018 and recently upgraded. I noticed the floor was soft in the bathroom. First by the exit door but in total, an L shaped section starting in front of the tub and ending past the door. 

I have some time this weekend and decided to see if I could fix this. Remove the tub, toilet and vanity and start pulling floor. Jayco floor system is essentially a luan/foam/luan sandwich with what looks like aluminum tube framing for the floor support and everything glued together. However what i found really killed me. 

Under the tub in the corner is basically disintegrated and all that remains is the underbelly cover. Miracle no one went thru the floor. Tub support was pulling it's weight and more. 

From what I can see, from back towards front, bottom luan is pretty much gone past the black tank and then hits a tube, and seems to be in good shape past that. Going driver's side to passengers side its gone wall to wall, probably more as well but I dont want to think about having to get under the wall or bunks on the other side. Top layer of luan isn't as bad, maybe half as much affected but its all getting removed in the end. In the pics, the sagging underbelly is essentially where it delaminated from the luan. 

What's scaring  me is the thought of having to drop the black tank to fix this. I could probably strip all the bottom luan from underneath with the underbelly rubber amd black tank off and then add plywood once it dries out, if the top luan isnt wet but is that even a diy job? 

Im looking for some insights and advice, i have some questions and any responses are greatly appreciated:

Is this something I can DIY with some time and ingenuity? 

Is it worth it to bring this to a shop to fix? The trailer was basically free to me so I dont mind paying, but there is a point where id just say get a new one as its 10 years old. However I have one more trip planned in a month and id rather not cancel if I can resolve this. 

What would a repair like this typically cost? 

And anyone have recommendations for repair for central NJ and eastern PA i suppose. 

Thanks all. 

Soft Floor Jayco 2016 26BHSW-Impending Disaster