If you can, match your tie and flashes to the maroon stripe. Next best, match the tie to the hose. You could get away with a patterned tie if the major color is correct. And you wouldn't be setting any precedents to wear a different tartan, particularly if it is appropriate somehow. For myself, though, I prefer a solid tie or one with some little pattern repeated over solid, like deer heads or something.

Another idea, match the shirt and hose one color, and the tie and flashes another. In that case a white shirt goes with white hose. White hose are never my first choice, but to most people they look formal enough.