Brilliant study. It was very well presented. I wonder if you were to increase your walking pace and duration, would the increase in body temperature from physical activity eventually bring the temperature under the kilt back up.
I also understand that the highlanders when sleeping outside would get the tartan good and wet, this actually increased the "R" value and the fabric would actually steam dry while they slept and keep the occupant toasty warm.
I think a study of how many drams it takes to increase the temperature under the kilt would be much more scientifically valid