When I ride rallies with our local Vespa club we take the big long truck approach. We have a technique, though, that makes this work. We have a couple of folks who serve as traffic blockers at intersections. They park their motorcycles in front of the other lanes and signal to the cars not to go. Then when the final scooter gets through, the guys blocking traffic go, race up to the front, and do it again at the next intersection. The traffic waiting seems to get a kick out of all the scooters and they don't seem to mind.
I don't know if this is legal or not, to tell you the truth. But once we approached an intersection, everybody got set to take their places, but a Highway Patrol officer happened to be there, so he took over blocking traffic for us, smiling and waving at us as we went by.