Maybe something to think about (WDS or another publisher?)

[Plain Ian]

On the march at 4 abreast a 125 yard hex can hold about 500 men,  since the average regiment would normally be 3-400 men say 1 regiment plus wagon per hex.  At 1750 yards per mile say 14 hexes per mile or about 5-6000 men, about the average sized division.

Deployed for battle is another story, at Gettysburg Longstreet's Corps of Hood & McClaws divisions and 2 battalions of artillery, close to 15,000 men, were deployed in an area about 1.5 miles long and a half mile deep.

Well to continue the dream here is a quick map I did. I took a snap of the MMP game Roads to Gettysburg on Boardgamegeek and put it on the ACW Gettysburg map. 

I blew up hex outline by 600% and added a few to see how it looks. The hexes in ACW are 125 yds across so this is still short of a mile but seems to come close to the MMP boardgame? 

Funnily enough the map/scenario I used is the Terrible Swift Sword Variant 1 with Devins Bde on the Chambersburg Pike and Gamble just below him to the left of Gettysburg! It kinda matches the boardgame!