At the risk of asking a stupid question ,,, do your vehicles stay registered with the same no forever or , does the owner of the vehicle have a designated reg no for each vehicle they own ?
In UK vehicle retains the no whoever owns it .
"New" Jersey - it depends.
Truck, Car, RV, Motorcycle, trailers - registration number plate is new with each owner. But an owner can transfer his existing number plate to a "similar" new vehicle if one desires, otherwise they are turned back over to the Motor Vehicle agency. We really do not own the plate, it is basically on loan.
Number plates only come from a Department of Motor Vehicles office (or online/mail for a courtesy plate)
Boats, watercraft etc are different. Since we don't have plates for boats, we get a registration number that is affixed to the hull. That number stays with the boat for life as long as it stays in New Jersey, regardless of the number of owners.
Except if the boat is "Documented" (USCG documentation of the vessel and all liens).
The documentation number is etched or permanently attached to an inner hull surface and it stays with the boat regardless of owner or State the boat is docked in, and State registration numbers are not needed.
I do find it odd that one can get a number plate made up at a motorcycle event though

I had this plate made with my New Jersey registration number several years ago while visiting family in England.