For me the Historical Plates work. I don't drive the car often, and when I do it is within the rules.
The plates are white with red lettering, and goes good with my red car.
My car was a black plate car, but I got personalized plates back in the 80's when I had no idea the black plates should be kept. I have photos of the car with the black plates and old reg papers with the numbers. I could get the black plates put on, but I like the Historical plates.