I ran across this site regarding clothing during the gold rush, same time frame as TITP. http://www.directcon.net/wander/GR.htm.
I haven't been able to read much of it, but I'd like to get back to it some time. Seems to have some interesting stuff.
The Intermountain Living History wiki also has a brief summary of clothing and links to more info.
I also found the link to the Living History and Re-Enactors Conference.
I've been waiting for info on this, but I guess it's just not coming! I'd love to go this year, but it's just so hard being a nursing mom!