First, ...Welcome to the CRG site...
Bottom line (especially if you're being 'watched') it appears you're going to have to mount the front plate. Short of getting the factory plate bracket (which you could through GM), ...but it sounds you don't want to go that route....
SLP does make (or did, ...implying past tense) a front plate bracket (SLP PN# 59388, "Bracket, 1993-02 Camaro License Plate" that mounts to the 'chin' of the front nose of the car. It's probably the only way to "legally" meet the state's requirement of 'properly displaying a front plate. This bracket will allow you to mount the plate without hindering the grill area.
I've seen others actually mount the plate directly to the front air-dam, ...but honestly I don't know how they got away with it.
Give SLP a call... (732) 349-2109, ...or check
http://www.slponline.com The bracket is only about $20, ...you may as well order it. Maybe even consider keeping a copy of your order WITH your car until is shows up, ...just in case you get pulled over again, ...you'll at least be able to show due dilligence in correcting the situation...
...best of luck with it...
Kevin