This deviates a little from your original concern but is in keeping with modesty while wearing a kilt and don't believe I have ever seen this addressed here on XMTS.

I have both an 8 yard knife-pleated kilt and a 4 yard box-pleat. While I like them both, one aspect of the 4 yard is that it requires a little more attention to modesty while seated. With all of that extra material in the "tank", there's just more material that naturally lays between one's thighs. Not a big deal, just different.