I may be mistaken but I believe that the Submarine base at Holy Loch was/ is used by both US and UK forces and has a dedicated tartan named Polaris after the style of missile carried in that era.

Another option would be the US Navy Edzel which he could wear in the spirit of camaraderie on the high seas in the same vein in which so many in the states wear Black Watch, Gordon, etc. in solidarity with the Highland regiments.