I have had a couple experiences running w/o front plates before Michigan dropped the front plate requirement.
I used to have a '66 Shelby GT350 with the fiberglass "racing apron" front valance on it. I had a tranny cooler mounted in it, and a plate on a swinging bracket suspended from the grille above. At any speed, the plate would just swing up, out of the way. Got stopped in Ohio one day for that..."I stopped you, because you don't have a front license plate on your car"....."Oh yes, sir, I DO".....when he walked back up toward the front of the car, he was absolutely dumbfounded that there WAS a plate there! Thank GOODNESS he didn't touch it, or notice that it would swing up.
I used to have a plate attached to the spoiler on the front of my Pantera. The spoiler and plate took on a bunny (there's those bunnies again) on the highway one night. The plate was too wrinkled to put back on. I carried it with me under the seat. Only time I was asked about it was one afternoon crossing the border to Canada. Told 'em I couldn't find a new bracket since the bunny incident ('ya know how hard it is to find parts for old foreign cars....) - and they sent me on my way.
Fortunately, since then, Michigan has become a "one-plate" state.
cobrajeff