Another option that I'm beginning to think about, especially if I can resolve the remote issue I mentioned before, is hooking the camera to the front end of my front rack. I purchased a set of Nice Racks, which have platforms on both the front and rear racks. The racks are about the same width as my camera and it shouldn't take much to rig something up to hold it. Obviously, that set-up requires 1) 2 cameras - one in front for the road and one in back for the other people on the tour; and 2) cameras with remotes. It's certainly something I want to look into.
49 minutes ago