How are you going dispute that? You got the obscured plate, you've got the law on the books, you got the ticket? Or are you hoping that no cop shows so you can get off on that technicality? What will your argument be?
Agreed.
Also, that pic of the police van doesn't really mean or prove anything. The van is parked, the photo taker could have easily put the rack on then snapped the pic. (Not saying that's what happened, but if you tried to present it in court, it's easy to say that's what could have happened).
Besides, even if an officer is breaking the law that does not make the law invalid.