Chris,

Since the guerillas were "fresh off the farm" they probably used civilian type saddles of the era, modified to field service. I am sure the guerillas obtained model 1859 McClellan saddles at points during their actions against the Federals.

Here is a site that may help. It is about reproductions of saddles of the era

http://www.ushist.com/saddles-tack/period_saddles_military.htm#item-m1

Len