I don't know about civilians actually participating in the battles, but Gary Joiner has edited a volume for UT Press that apparently has a great deal of civilian experience content, called "Little to Eat and Thin Mud to Drink: Letters, Diaries, and Memoirs from the Red River Campaigns, 1863-1864".

Even though most places have it as a May 07 release I believe it is available now. You might find something in there of interest.