one way vs two way tours

I would like to create a tour of a canyon. The challenge I have is that I want to create some general information about the canyon at the beginning of the tour. The tour can start from either direction though.

I was thinking about creating two different routes so that I can set the triggers differently for the same file. But, if tourguide uses proximity for the POIs then no matter how I set it up it will give the overview audio at both ends of the canyon. Anyone know how to get around this?