On their website, USAK describes a method using a towel as a 'template' to view and then decide on the length you prefer. I found it to work quite well for deciding on both comfortable length, and height, within the acceptable parameters. It gave me the opportunity to both see, and feel, what the different heights and lengths would be like.

If you have already sent off your measurements perhaps you could double check using this method, and still notify the kilt maker in time if necessary.

I hope this helps,

Brooke