1) Have you been the "recipient" of a GT with it's fog lamps on? You may understand why the officer stopped you...they are bright (DOT approved or not)...
2) The fact you have the ability to turn them on/off (i.e. don't come on automatically with the your lights) is not helpful to your case.
I use my fog lamps in bad weather (i.e. rain, snow) and on lonely back roads. Besides having to replace the bulb is a PITA...so I would recommend using them sparingly.
Also, don't forget that your Stang can reach 150MPH...but that's not legal either.