I would recomend 1 turn = 1 day.
It would take forever but it would allow for the largest micromangement, and precision decision making.
Nothing says you have to play through the whole day, if its just troop movement or what ever you can just go through the day and thats that.
The Hex bits would have to be quite small
so it would actualy take 'months to get to Madrigal on Foot' from the Cloudspine.
Also I remember from Myth TFL that Shoal is a small town 4 miles away from Covenant, according to the Map though, if it takes months to get to Madrigal on Foot, Shoal couldnt be just 4 miles away, so things like this needs to be adjusted.
One Might also be able to found and build new cities (at great expense of course), on the Light side. Need to figure out how the light armies pay for their stuff, likely gold and silver, which means there are mines to be run, need to check into this too.
Thats all for now.
DarkSword