I don't have any data to back this up but I feel a lot of de-lamination problems are due to over-occupancy. Humans breathing, cooking, bathing, etc, etc, produce a lot of moisture. These trailers (especially the lower end ones) just aren't setup to absorb that moisture. This is probably one of the big reasons manufacturers void warranties for full-time use (not sure how they'd know unless you told them).
I see this pattern with houses and apartments. Too many people in a small apartment cause all kinds of problems to the building from all the moisture they produce. And very often there are more people living in a given apartment than what it was designed for.
It absolutely amazes me how much condensation in on the inside of my 5th wheel in the morning after 5 people have slept in it. Along with maintaining the exterior I always make sure and dry it out really well after each use. I leave the heat running on a low setting, leave fans on and a couple windows cracked for a couple days after use to make sure I'm not sealing up bunch of moisture.