Well, he said he wanted to go to "Jackson" and offered a large sum of money for the ride. We know he didn't mean Jackson, WY because he got out when he understood that's where his ride was headed. Jackson, ID is a 5.5-6 hour drive away which would make the the offer of the 200 bucks sensible. It's also on the Snake River, which he said he'd been following:
jackson idaho to grand teton national park driving at DuckDuckGo
Maybe someone else recalls when that sighting in Idaho was. Perhaps they went to Idaho after leaving Yellowstone. If that's the case (and I'm only speculating), these are long distances.