Just print out the law and keep in in your wallet. If they pull you over, just show it to them. There are a finite number of police in the area you would be riding in. If you show the papers to enough of them, you not only educate them, but you give MBers a good name with them. Word will get around.
In N.C., the law is that any motorized two wheel transportation, with an engine of 50cc or less and with a top speed of no more than 30mph, is considered a moped. No license is required, no registration, no title. You can ride on *any* public road, as long as you keep to the right, wear a helmet, and are over 16 years of age. I have a print out of the 'technical' law, and just keep it in my wallet. I've never been pulled over, but I do have police drive by and check it out. In fact, I was dressed as Michael Myers for Halloween, and rode my MB. I had a speaker on the front of the bike, with my Zune attached playing the Halloween theme song over and over. I would creep up behind people, and fire up the engine. People would jump out of their skin. The police saw me, and just smiled and kept going.
I also train in MMA (Mixed Martial Arts), and there are alot of cops there. They are just normal people, and the good news is I can beat on them without fear of jail time. LOL.