James,
I would go with something like the tin lantern in the upper right corner of FCK's picture. A relatively small wooden box will hold more than enough beeswax candles (I think they were sold this way back then) and would produce enough hours of light. (Daily life in a Covered Wagon page 40) In my thinking if it would have existed in the Civil War era then they would/could have been seen on the Plains. May not want glass in it but not a bad idea. The lanterns with slits would work also, mine just does not produce enough light to satisfy me.
Remember the best hides where obtained during the winter, so they needed a campfire or stove to stay warm even in dugouts. That is where I believe most of the lighting came from. Even in summer they needed to cook at night and still had the campfire light.
PS: I also like the idea of the fold-up or collapsible lanterns. (Arms and Equip Of the Union page 223)