I really like the idea of the players and GM working together to create their wagon train map and then asking players to add obstacles and advantages at the beginnig of the campaign (as well as each game session). I blends a great visual pacing mechanic with the opportunity for any player to influece the types of challenges they will face and stories they will tell. It sounds similar to John Wick's idea of the Dirty Dungeon (implemented in Wilderness of Mirrors), which is a great GM ninja trick I awlays keep close at hand.
This is complemented nicely by players and GM also creating the wagon train itself and then tieing its attributes to to the PCs who take on leadership rolls for different jobs on the caravan. It gives the PCs a great idea of what their characters are doing day-to-day and gives the GM a clear target for who might be affected by obstacles on the trail.
[5 of 5 Stars!]