Just was hit with another thought regarding the rentals -- something that would be a good idea with probably a good bit less red tape to start with and get some ideas as to the accident and damage rate etc -- if you've ever been to any kind of auto racing -- indy, nascar, drags, etc -- you always see the booths where people can rent the scooters, golf carts, etc for use at the track -- same thing at events like Jazz Fest where people can get wheelchairs, rascals, etc to use -- might be worth it to hook up with an event promoter and test market the product in a more controlled environment, both to collect data and to see how the demand goes.
Something like Internext would be a great place to try it but I don't think you'd get the Venetian or the Sands (tho I hear we are moving to Mandalay) to agree to let you do it