"I've learned that for costumed occasions to switch to trousers. It reminds people that I consider kilts as clothing"

I agree with you, G.! The kilt is clothing, NOT "costume". Whether worn at a reenactment or a day at work. It may have a "historical" context (I own a plaide and two philebeags, nothing modern), but it is still a piece of clothing, worn as such, and considered (by me, anyway) to be no more remarkable than wearing trousers. They are NOT worn anywhere they could be considered as "costume".

Jim aka kiltiemon