I agree about the lack of red in the US Army Tartan, a shameful oversight. When I was at Fort Sill two years ago I picked up one of the embroidered cross cannon patches that were worn on officers hats in the late 1800's. I put to pins through a piece of lether and glued it to the patch. My kilt pin(s) miniature Vietnam Service Ribbon, Unit Crest, and the cross cannon patch.

I could also see a simple red patch, similar to the patch on the Balmoral, with the brass cross cannons, or unit crest.