The trick is to be uniform. A group can look amazing if they're all the SAME, regardless of what they wear. (Jeans can be hard looking the same. I'd go with black slacks and marching band shoes.)

The judge is supposed to be going off the music, and most judges are teachers, or used to be teachers. I think they understand the difficulties of this year. If you play well, you'll do well.

What you wear is two-fold: 1. first impressions that can be made in anything if it looks good and 2. getting the kids in the right frame of mind.

The latter is your main obstacle.