For what it's worth, in Scotland all of my high church Anglican buddies tend to wear "civvies" to most events, and only wear clericals to civic events-- that being the case I'd suggest that you go with the black Argyll jacket, three button waistcoat, dress shirt and black bow tie. I think the flashes in the appropriate liturgical colour is a brilliant conceit, and I'd endorse it 100%! (I have a friend who is a retired Admiral who always wears one red and one green flash...). Incidentally, they all wear their family tartan and matching argyle hose.