|Down here in FL, pretty sure it's the UV and heat that kills the plastic.
What type of UV coating do you use? Seems like a 2k clear might be the way to go, although would definitely need to be prepped correctly before application. Nice thing about that is it could be sanded & buffed a few times before needing to be redone.
Best of luck in all of these ventures. Nice to have some folks that show continued interest in producing parts, especially since Nissan has shown little interest in supporting their older marques. Hopefully the cost on these won't be prohibitive ;-)