I'm not local anymore, so take my thoughts for what they're worth...
I'd actually suggest designing a course that's safe in both directions. Everyone would have the opportunity to walk it in both directions in the morning and they could take a quick refresh walk in the afternoon. I know of at least one of Brian's courses that we ran at one event and then reversed at a subsequent event. You might loose a little bit of course diversity, but IIRC, I did well in one direction on Brian's course and horrible the other. And as a bonus, nobody has to redesign or rechalk the course.
If you allow bicycles for 'walking' the course, not everyone will have one, so allowing them won't cut the time. Since the rules do technically prohibit them, somebody will bitch sooner or later. Since the gain is negligable and the reward is listening to people cry, just let everyone walk the course.