When making up your mind, I think that this will be of interest:

The information held within The Scottish Register of Tartans for the "Leatherneck" tartan is shown below.

STA ref: 3612
STWR ref: none
Designer: Hall & Macleod
Tartan date: Not Specified
Registration date: This tartan was recorded prior to the launch of The Scottish Register of Tartans.
Category: Military

Restrictions:

Registration notes: Designed by Bob Hall and R H Macleod for the U.S. Marine Corps Historical Foundation. Does not have the sanction of the Corps but is sometimes sold as the 'U.S. Marines.'

The last paragraph is, I think, the most important, also note - there are no restrictions.

Regards

Chas