Mine's center mounted, we have to have them in Maryland on both front and back. Got a nice set of smoked plastic covers for mine and they look nice.
I had your problem back in 1970 (ha ha). I had a brand new '69 and 1/2 Z-28 Camaro and I scoured the country for one of those USA -1 License plates. I had it on the car about 2 days and got pulled over. I've been obedient ever since.

Good luck - Pat