It should be that simple....not sure what state you live in. Here in Minnesota, the YOM plate needs to have at least one letter on it so as to not conflict with certain state vehicles, which have all numbers. I did this with my Meadowbrook and that plate isn't even readable beyond like 10 feet! LOL
Otherwise, if your DMV doesn't allow it, you can put on any plate you desire while you're at a show or gathering. Then, if it were me, I'd conveniently leave them on and if I was ever pulled over I'd just say I left from a car show and forgot to change the plates. The cops around here don't even bother with us car enthusiasts. I could put on any plate I chose ?