When I make a 4-yard box pleated kilt, I don't cut out in the inside of the pleats, because there is no need to. My point of reference for these kilts is always the historic kilts that I've had the benefit of examining first hand. None of these had the pleats cut out. Again, there is no need to.

On a 4 yard kilt, the pleats are not deep enough to overlap one another much, so usually you only have about 3 layers of thickness of the cloth. It's enought to provide some body without being bulky. For the same reason I also don't put in a full canvas lining in the back. I don't need it. Because I didn't cut out all the pleats, the heavy weight wool that I usually use (even the medium weight) has enough thickness to maintain the shape of the kilt. (I do put in a 2" wide strip of canvas at the waist line to add support where there will be stress from the straps and buckles pulling).

When I make a 5 yard knife pleated kilt, it's a judgement call. Usually I leave the pleats whole and intact. However, on some men, with some tartans, the pleats end up being deep enough that there is considerable overlap at the waist, and if I feel the bulk is too great, I'll cut away the pleats.

I would never do any kilt with more yardage than this without cutting away the pleats, as it creates far too much bulk in the back. I noticed the same thing about the Stillwater kilts I've been able to examine in person. The back is almost cushion-like. I've also seen some amateur made kilts with this same problem.

~M