for the purposes of creating a sort of Scottish "ambiance," kilts are a lot more appropriate than tuxedos, even if NEITHER are historically accurate.

A lot of Scots find it pretty offensive to have their history Bravehearted up like that.

There aren't many operas set in the early US. One is Verdi's Un Ballo in Maschera, set in colonial Boston around 1700. A similar approach to historical authenticity would be to have all the cast in backwards baseball caps, saggy jeans, gold chains, and designer sunglasses.