“Journal of a Trapper (1834-1843)” by Osborne Russell provides a glimpse of the hardships faced by trappers who trekked through the Rocky Mountains in search of beaver pelts.  It’s basically a series of journal entries and it’s not the most descriptive piece of literature, but there are some memorable moments about hunting mountain goats on cliffs, being attacked by hostile natives, and having to trek through deep snow.  I too have been seeking non-fiction adventure stories and I think Outside Magazine or some other similar source listed this title in a lineup of such stories a few years ago.