Delamination

I would say another possible cause is use of the TT during cold weather and not exhausting out moisture laden air. Moisture in interior air will migrate through the insulation to the outer skin and condense on the cold surface. RVs don't have a moisture barrier on the interior side of walls & ceilings like buildings are required to have.

If the TT is a FR product, it can't be a Cougar as their parent co. is Thor. A letter to the Trailer Life mag. could be another option. You might also inquire on the FR forum if you haven't already.