You have a tough row to hoe. Back in those days many county seat's locations were calculated as being a day's ride from the edge of said county. That's how counties were established. Of course there was always a post office at the county seat. Twenty miles was close to the limit. CW infantry units could march about 15 to 20 miles in a good day...I say COULD.
Look for creeks and springs along your map route. If at ever possible the troops camped where there was water available, be they rivers, creeks or springs.
Hope this helps.
Gary