I'm decades past college now but put myself through undergraduate school working summers at a fiberglass factory making front ends for cars. Never thought the skills used there could come in handy but here we are.
Although my trailer is under warranty till this fall, living in MN as I do addressing severe cold induced trim cracks sounds like it could easily end up becoming part of yearly spring maintenance.
I contacted NuCamp today and asked what type of plastic the trim on the outside edges of the trailer is made of as the repair approach differs depending on the type of plastic. They helpfully referred me to the company that manufacturs the part for them (Duoform Plastics). I called Duoform and they said the plastic is made of, "ABS plastic with a clear solar coat cap as a UV protectant".
Here is a short summary of what is involved in repairing ABS plastic: https://www.hunker.com/12367945/how-to-repair-abs-plastic