There's a guy around my neighborhood who takes his stocker in the bicycle lane of a 5-lane-wide roadway here in south FL, a major N-S arterial route, US-1. I'm surprised he hasn't met an untimely end yet from a texting driver.
With a lay-down posture, I'm sure the modified scooter rider could go much faster, but you probably need to have some semblance of the original device for the class.