It can be done, get the lights and you're a moped. No lights and you're an illegal unregistered moped. You have to go in there armed to the teeth with answers to all their questions. Say everything start to finish without pause. Start out with a little comment like "sorry about the furlow days I know you're under a lot of stress right now, I have created an assembled vehicle, a moped, I'd like to register it." "It has all the components and specs of a moped, the VIN (bike serial#) is ________" "I purchased the motor online and still need to pay tax for the motor, please add that to my $15 registration fee." "I understand this is not your everyday transaction." If they still balk, ask to see a manager and get an explanation in writing why they are refusing your moped sticker. If they won't do that ask for an employee number. They usually will give in then. More trouble than it is worth. Report back everything, good luck. It is not always easy to be the first, but remember you are making it easier or harder for the next guy so do your best.