I think that I would use a "modified" ketchup and mustard pleating: instead of centering the pleats on the red and yellow stripes, pick the stripe color you like best, and alternate that stripe's pleats with pleats centered on the brown beside the other stripe. You'll still get two pleats per sett, but it will make the back if the kilt much less busy. Almost a cross between ketchup and mustard and lawn chair.