Map/unit scale in a Civil War game I'm designing

I’ve been working on my Goldilocks Gettysburg game for many years and have come across an issue I need to resolve. It’s a brigade-level game. I need to decide what the scale of a single hex is, and how many troops would, in a defensive posture according to the tactical doctrine of the day, fit in a single hex. The basic question is, for example, how many yards would a brigade of 3000 effectives occupy in a defensive line of battle? Thanks for any wisdom