I suppose really it would help to know what brand of coach you are looking at. The kinds of things that should concern you would be some of the cheaper brands that may use flake board for flooring. You should be able to look up what was used. I think overspoke when saying pressure treated. But often your better manufacturers do use marine grade, which should be water resistant.
When you talk about delamination, not all manufacturers use laminated construction. Some manufacturers glue the fiberglass directly to the aluminum studs. Usually there is rigid foam in the walls. Problems happen over time, so as long as you are keeping after things, in your better built coaches, you should not have structural damage. If you are full timing, that is to your advantage, as you will be constantly airing it out, so it will have time to dry.