I think in most non-Scottish (unlikely to see another kiltie at the ball) formal settings you could get away with an Argyll jacket if a PC is not available, preferably with waistcoat, and a nice tie (bowtie or cravat) with a collared dress shirt (not button down), classy matching or white/cream hose and shined black dress shoes/ghillies, and a nice dress sporran with silver cantle. Afterall, your kilt is going to make you stick out already, and most likely nobody is going to be too picky beyond that as long as your outfit has black coat with silver buttons and you have the appropriate dress accoutrements to go with it. Only a true kiltie would recognize any discrepancies you might have from the "true" Scottish formal look others have described above.

Argyle vs PC at a formal event: