I'm no expert But:

In Thompson's Book "So your'e going to wear the kilt"
this book is sort of the unofficial guide to Kilt wearing in the U.S.

Thompson states that they should be tied up in a bow and the ends trimmed short. He futher says that to leave them long and trailing behind your head
makes you look like a school girl.

But He is gone now and things may have changed
thats why Hamish needs to write a new book or at least make a video