I am actually writing a book on the subject as well. It comes from over 25 years of archival work, and outdoor field experience as a primitive outdoorsman, living historian, and gold prospector. I recommend getting University archival login. This will give you access to diaries, publications, documents and other ephemera you won't find on google.
You have your work cut out for you but it will be rewarding. I look forward to seeing how it turns out.
-Dave