Reading this thread just shows me how far I have to go! I am admittedly tired after a long day of work and two drinks, but I realize how far out of my league I am in this whole kilt making business.....Yay, the challenge of learning new things ! (The F-H.C.A.G.)
I'm not convinced as your sewing skills are much more advanced than mine. I view these pleats as just another technique, the layout and sewing are where the skill is required. (I trained as an electronics engineer, so I suppose that I am looking at cold logic here.)

There does seem to be some confusion about military box pleats. The real problem is that they are mis-named (but we're stuck with it.). What they really are, are rolled knife pleats. Thank you for finding that link Wompet. I just spent a couple of hours looking for it! (The search engine does not like "box" because it has less than 4 characters.)

Normally, these kilts are pleated with one sett to the pleat, although the kilts worn by the Royal Scots and the Canadian Scottish (Hunting Stewart.) are pleated to alternate stripes. (Red, yellow, red, yellow etc.) I pleated my Hunting Rose kilt in this manner and had 8" left over from 8 yards.

That was because I used 1 1/2 setts per pleat. (27 pleats.) To do it that way for 31 pleats would require 9+ yards. I can only assume that the military Hunting Stewart kilts are pleated alternately with 1 1/2 and 1/2 a sett. This would average 1 sett per pleat, but the pleat depths would also alternate between 1 1/2" and 3". I have never seen one of these kilts up close so, does anyone know?

[Fraser and Kirkbright will weave a batch of 13oz PV in Hunting Stewart if there is enough demand. (Hint. Hint.)]

Progress update: I finally got the pleat folds to butt together and lay flat. I just put in the steeking and reinforcement strip. (The pleat measurements ended up spot on target!) The canvas is next.