I honestly think you're going to have a hard time getting anything to bond to the OE panels in any long term kind of way.
If you use them to make a mold you can just repair the mold or the fiberglass afterward, both of which would be easier than repairing the surface of the panels.
I did that with my A-pillar trim. It makes them look a lot better but I don’t think it’s going to do much or anything at all to keep the trim from deteriorating and cracking further. As a short term fix it works, but in the long run I’ll either need to find other panels or cross my fingers and hope someone reproduces them at some point
