Don't waste your money on fiberglass cladding unless it has been previously installed and the fit and finish are known to be acceptable to you.
At one time (perhaps 25 years ago) it was a suitable alternative to factory pieces for the more sought after factory parts that were expensive and becoming difficult to source.
About 10-12 years ago, the original producer sold his stuff to another firm in Southern California. The parts the 'new' firm produced were expensive and total junk. They were distorted, hand-trimmed with a sabre saw or sawzall and surface condition porous. Each piece would require days of labor to fix and prepare for installation.
I had an owner that purchased $2500 of junk from these guys and expected me to fix their junk parts and install them. I refused. IIRC it was 2 rockers, 2 corners, and 2 front arches. The rockers were so stiff they could not be 'bent' into position, the lamination was at least 3/8" thick, the upper lip that sits on the support was so thick, with no recesses for the rivets, that the door couldn't close. They weighed a lot. Junk. For $2500. 10 years ago.
