Have you thought about using your skateboard with the bike? I was given an old electric scooter, which was not street legal. I striped and modified it so I could bolt it to a TRI Hitchhiker, a one-wheel trailer that originally was used for hauling a child behind the bike. I removed the seat and pedals and bolted the modified scooter frame to the dropouts and chain stays of the trailer. I extended the throttle cable so it could be placed on the handlebar, of course! I've ridden this rig and it's quite fun and safe. Below are photos of the end result.
