1. Get in/on with a drum corps and get corps experience
2. Learn to do color guard, which is a highly marketable skill.
Doing one (or both!) of those will GUARANTEE you an entry level position when you graduate. It's not absolutely required, but if Big Suburban ISD is looking for a third director, and they want someone with a strong marching background or with color guard experience, they'll hire you in a heartbeat over the guy/gal who doesn't have either, especially if you can teach.
Finally, consider this. Do you want to be a band director because you love marching band? If so, get a performance degree and then go work with drum corps, or get a composition degree and go write marching shows. 66% of the school year is concert band. If you don't love sitting down and teaching march style, notes and rhythms, and how to make a good fundamental sound, don't be a band director. There are plenty of careers you can choose that are in "marching band" but don't require you to teach if that's something you're not interested in.