I would imagine calling NJ DOT direct and asking them would more than likely answer your question.
Here in PA, unless you are an authorized shop, by the state, you can't produce any street signs of any sort for other than private property. Parking lots, inter-state roads, highways, downtown, ADA, residential or commercial properties are all taboo. I can't even put a 'No Left Turn' sign on my own property unless it's approved and gotten at a legit DOT shop.... and we have the knowledge and full capabilities of doing so.
No loitering or no parking on private property we can do all day long.