No registration or anything with a 50cc engine?

[MattW]

I live in Nevada. What's the law concerning a vehicle with a 50cc engine? I would like to make a motorized couch, but I obviously don't want to have to register it, insure it, etc. I want this thing to be street legal (I'll have all the lights, seatbelts, etc.), but I don't want to register it. Is this legal?