Please remember that this years run of X Marks Tartan fabric was in the Polyester/Viscous blend from Marton Mills.
This fabric weighs in at 12 oz. per Fabric Yard.
In my opinion this is a little light for a good Box Pleated Kilt.
I've seen Box Pleats done in 12 oz. fabric and it works and is great for really hot weather but the rule of thumb for Box Pleats is, the heavier the fabric, the better.