for the loveless alley cat here in Ann Arbor during February we had all the riders walk a good 60ft away, had them all turn around, and we then proceeded to take all their bikes and move them around the corner of the park(the diag on state and n.Univ) where we were starting. It added a nice little bit of chaos to the beginning because they had no idea where their bikes were. We actually had a crowd of people passing by standing across the streets from us watching to see it start, i think they got a kick out of seeing it also.
And instead of regular check points, we had them take pictures of themselves at each check point, which resulted in a photo receipt that they made it to the checkpoints (it was also nice and chilly out, and we were short handed to have enough people manning check points) and it worked out pretty well. More check points, shorter distances around town, and no waiting in a line at a check point.