If I might?
I would think that if there appeared to be enough demand for a company to produce a screen, they would. To that end, I suggest writing the companies that make screens, (Ahem... National Cycle comes to mind) and ask them if they would consider making a screen for Z bike.
I did, and I hope that enough people do.
Also, FWIW, it wasn't as much the Ermax Screen as it was the Kymco design for mounting that was the problem. Ermax didn't really do much to get past it, and they did produce a good quality product. It was the instructions that were lacking.