I know Hat has TONS on their plate, but in light of the mention of Von Lettow's troops, I would like to suggest a few other specialty sets for consideration!
Lovat's Commandos at Normandy! Yes it's history vs Hollywood, but I would love to see the beret wearing troops with their piper & sweater wearing commander!
WW2 Scottish Desert troops wearing Balmorals! Yeah, I know most wore helmets, but I think a set exclusively wearing the Balmoral would indicate them more as Scottish troops!
WW1 Scottish infantry wearing Glangarrys! There is a set of virtually every army wearing soft caps. Why not the Scots?