First, I think the idea of wearing the kilt to your prom is great. My son tells me that some proms will not allow someone without a "formal" outfit like a tux. If that is so then you will have to go formal. If not then look at some of the photos of Prince Charles otherwhere seen on this site. You can look really sharp without spending a lot. As to coordination with your date: the tie can be coordinated with her gown and a pocket handkerchief if you use one.