I never got pulled over by a cop for it but if the guard doing gate duty at the base feels like being an asshat, they can pull me over for it.
I suggest to anyone running no-front plate in a front plate state to either just run the plate or get a Craig's bracket that attaches to the front bumper without any drilling or leaving any marks. This is what I did on my old 98 and will do again when I put a Cobra bumper on this 2000 but for the GT bumper... its got a flat spot anyway so might as well just put the plate on it.
2000 Mustang GT Steeda #0048
Just because I give you advice, doesn't mean I know more than you. Its just means I've done more stupid ****.