Thanks, Glenda. Asking the same question at the Santa Fe Trail email group got an answer of several books on the topic, including one by Donald Blakeslee, another by Alfred Barnaby Thomas, and a third (The Pecos Indians and New Mexico, 1540-1840) by John L. Kessell. He may be related to the Ron Kessell you mentioned.
Anyway, thanks, and I plan to check for these books at the library. What I learn may eventually go onto the "Interactive Santa Fe Trail" site at http://www.ku.edu/heritage/research/sft/index.html