As a retired Marine Master Gunnery Sergeant with over 33 years in our Corps, I can tell you, from first hand knowledge, that I wore the kilt all over the world when on my own time. I can't remember a negative reaction. When on your own time, you can pretty much wear anything within reason. And in my mind, the kilt is within reason.

Before I forget.....

from Sunny Southern (just outside the back gate of Camp Pendleton) California.