I don’t know, if you’re far enough back that a cop not part of the procession escort can pull you over I don’t think you’re in the procession anymore.
I was the last car of a procession once.
The cops ‘trade off’ as the procession goes through each intersection, so the cop at the tail end is constantly changing...usually the guy who had traffic stopped at the previous intersection, who has to catch up.
We could tell that one of the cops was very suspicious of us, and pulled up alongside us, trying to peer in and see whether or not we wearing suits. He eventually satisfied himself and fell back behind us...but I can see how the last car can be hard to identify.
I’ve also been in processions where a magnetic sign is placed on the last car.