unless it is mounted in the front of the car, its illegal. This means any windshield, visor, or other mounting system is illegal.
Also, clear/smoke covers are illegal.
I have mine on the front. I had it on before the deer accident, and I scored a new bracket for free because of it (go go zip ties). Especially where the shop is, no need to get pulled over more often than I do.
Plus if you are worried about something stupid like the front plate 'slowing you down' you really need to make some power
. I agree they don't look good on the front, but rules are rules.