Basically what your saying is The new fascias will be Made-to-Order. Nothing wrong with that. I may be adding it to my Spring repairs. Windshield,A-pillar replacement@ Dave's shop.
I still think it would be it would not be unreasonable to have a Fiberglass Rear Fascia Option available. You could price it with a premium, for those that want it and and it still be a MTO part. Premium pricing would still keep the NOS stock attractive for those that don't want to spend the extra on it.