The "unclear" standard does not apply and is bogus as applied in this case. The plate was not dirty or unclear, nor was there anything hanging from the plate holder, thus this statute does not apply. You need to look to trailer regs. as this is an attachment causing the plate to be obscured. I recall reading a brief once on this issue and was convinced that a hitch rack, unless right up against the bumper) would not obscure from reasonable angles in a manner warranting a violation. Hang 5 bikes of a 2 bike rack and strap a DH tire directly to the plate frame - a different story. A travel trailer, etc. of course, but not something less than 2" wide, and certainly not without bikes on it. I also think there is direct case law on the issue. I just can't remember if was in NJ.
Either way, you will need to appear at least twice. The first time is simply to enter your plea, then they will schedule you to come back for trial - and make you wait hours. You may get lucky if the trooper does not show up (Suhr40, if you are able to respond, are they still giving adjournments if a trooper does not show to local traffic court?). I went through the process last year to be found "not guilty" of a snow shovel violation, but I had the benefit of being able to work on a laptop from the courthouse while waiting for my trial.