My state requires a front plate, with a few exceptions (classic, year-of-manufacture, street rods, old timers). I got pulled over once with my Saleen Mustang that did not have a front plate, let off with a warning. So I had to add a plate mount to it as the manufacturer did not offer one.
My smart came from Green Car Co in Kirkland, WA, and they mounted the frames on the car in new holes in the plastic body panels. When I changed to my second body panel set, I had to drill the holes to match, but since they are hidden behind the plate (even a Euro plate), it was not a concern. The holes won't rust ;)
Tom