Hi i went up there solo back in august of 08. I actually flew into Missoula and hitchhiked from there to the park, then used buses to get around. The buses on GTS road are really easy just show up and they come by. Clear maps and schedules and free. Hitchhiking in the park is easy. If I did it again I would fly into the airport near Kalispell and arrange transportation into the park then wing it from there.
For sites i just showed up at the BC ranger station no reservations. They give you a big map and a list of availability and you just plan your trip out sitting there. There was alot of availability although some of the busier sites were unavailable. But if there is really a site you want you can get it a few days out and go somewhere else in the meantime. For the car campgrounds on GTS road they have walk in sites readily available.
Solo is a little freaky with the grizz but now that you can pack heat just grab that desert eagle and go for it!
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