Car enthusiasts seem to get away with alternate plates around me. Sometimes plates from the manufacturer country, sometimes decorative plates resembling the local jurisdiction but being the car's name or year/model. Either there's nothing specifically against additional plates that are clearly "novelty" items or my local police just don't care. Now, if they're legitimate government-made plates, I'd bet you'd run into issues.

I'm sure you could add something that expands your plate info, but I can't see a solution that keeps your true plate visible (to avoid direct police activity) without also keeping your actual plate number as part of the character string associated with your vehicle. I do recall reflective letters being sold at one point to defeat standard speed/light cameras (plate is reflective by default, characters are not). But, still, with all the extra details the system logs with y/m/m/c, stickers, attachments, and damage, I regrettably don't see this being especially effective. But, I suppose, it has a chance to keep your unique vehicle unassociated with government records.... For now.