You might try "The 1837 Sketchbook of the Western Fur Trade" by Rex Allen Norman. It is only detail drawings taken from the works of Alfred Jacob Miller (the only artist to have actually been to a mountain man rendezvous) Obviously, any art books featuring reproductions of Miller's work are also recommended. For beautiful color photos from a modern-day buckskinner rondy I suggest "RENDEZVOUS Reliving the Fur Trade Era of 1825-1840" by Kurt Rhody. In a similar vein try "The Book of Buckskinning" vols 1-8 from Scurlock Publishing (Many articles on gear,clothing, behavior, etc of the mountain man, modern and historic)
For the detail-hound try "Firearms, Traps, & Tools of the Mountain Men" by Carl P. Russell. Also check out the Sketchbooks from the Museum of the Fur Trade.
Any one beginning to see a pattern in my library? <G>
Anyway, hope this helps.