I have 2 for the GT's from moweraxle dot com, but he retired, and just looked the URL is dead. I think I have a half dozen of Larry's plate mounts (for other cars), they are machining works of art.
California has a law requiring front license plates but I don't have front plates. In over 30 years I have had three fix it tickets for no front plate from $10 to 25. I pay the fine & don't install a plate.