Careful, klhansen, I put a topper on my front 1950 plate and eventually the plate cracked. Now the topper is on my front plate mount by itself.
I'll probably cut out a license plate sized backer (I have some scrap aluminum - part of a boat - don't ask) that I'll use as a support behind the plate itself. I did that for my replacement boat trailer license when
it the old one fell off, leaving just the two corners bolted to the trailer.