Picking a route across country after an apocalypse must be a dangerous balance between urban and rural. You probably want to avoid bridges and tunnels for fear that they are uncrossable. You want to avoid cities because of people and zombies, but you need access to gas, food, and water. I think it was The Expanse books that talked about how bicylces are the best mode of transportation in an apocalypse.
About the militia leader: Were there other women in the militia? In the land of the blind, the one eyed man is king. I really think they miscast her a bit. I think they were going for the sweet but cruel trope that you see work really well in movies like Cruel Intentions, Dolores Umbridge, Regina George, Gone Girl, Nurse Ratched. That type of character could believably be running a militia without a physical presence. They cast someone that pulls off the sweet but wasn't pulling off the cruel.