The area above the slide would be a relatively easy fix,(see my first post)the area on the slide is a large area and a big project, all the molding around the slide would have to be removed as well as the outer FG skin to see the condition of the substructure and to let that area dry out. I would probably seal the leaks and just use it as is. If you do a search on here some folks have fixed their side walls like this and you can see what is involved. I fixed both sides of mine when I first bought the MH, the passenger side repair has held to this day the drivers side lasted about 5 years and delaminated again, this side was always parked in the sun.