Yes I had that problem on a bedroom slide. You are correct, the slide had to be removed and the bottom replaced. I had this done at the Monaco Wildwood facility when Monaco still operated it. Cost was around $4200 and it took two days as the glue has to dry overnight.
I live over in Foley, AL and would be glad to look at if you wish. First thing you need to do is find where the water was getting in. I look at the wrong place and the folks at Wildwood found it on the side wall about two inches from the top and where the side wall joins the outside wall of the slide. I had thought it was the seals leaking. Originally Eternabond tape had been placed over the joint and covered screw heads. One of the screw heads had worn through and that is where my leak was. Could hardly see it and it just look like a black spot.
You may also have damage to the coach floor under the slide. I did but repaired that myself. Let me know 251-233-9227 if you want me to take a look at it with you.
Don't know of anyone besides Carpenters in the Pensacola area I would trust, and don't know if they can do the job. You might consider taking it to Wildwood for repair. They have all the necessary equipment and material to do the job correctly. That facility is now operated by folks that originally worked for Monaco. They have a water and electric park ($10 per night) and there is a dump station there. Make an appointment and plan on arriving the day before your scheduled appointment. You will also need to go to a hotel for the one night the coach will be inside the shop. On the day of your appointment (may have changed procedure now) they will evaluate the problem and schedule it into the shop the next day. The coach will be picked up around 7:30 am and returned to the pad that afternoon unless it has to stay in the shop for other reasons (glue drying).
You can contact them here:
Alliance Coach
4505 Monaco Way
Wildwood FL 34785
866-888-8941 or 352-330-3800
352-516-4144 or 321-516-4144
Alliance Coach
I have no interest or affiliation with this company.
Rex Darley 01 Diplomat 40 PBD