Having said all that, I realized I didn't have anything appropriate to wear in October in Michigan for the 1860s other than my black wool mourning gown and silk gown... And I wanted something a bit more practical! Katie was selling a beautiful dress length of plaid wool which I snapped up from her. I chose some style elements that are visually appropriate for the late 60s to fit with the 1866 date of the cabin (although it was inhabited well into the 20th century), but would still allow me to wear it for earlier events in the future. I chose a standing collar, slim coat sleeves, and a flat front skirt with box pleats, which tend to be features on later 60s gowns. What would have made it perfect is an elliptical cage, which I just couldn't afford for a one-day event! So I went with my regular 60s cage. I also styled my hair very distinctly late 60s, with emphasis not on the sides of the face but more on the top of the head, and with most of the bulk of the hair in a rather full chignon (as opposed to confined to the nape of the neck).
There's actually a lot of things I'm not happy with, so I will be fixing those things in time to wear the dress again in November for my trip to Gettysburg with confidence!