I attended a relative's funeral kilted. My formal MacGregor, suitcoat, black necktie, plain white shirt, hose. I would not go to a funeral in a Prince Charlie, nor a bowtie. Funerals just aren't that dressy.

On the downside, if you are the only one attending a funeral kilted, everyone will assume that you're there to play the pipes. After being asked by the funeral director when I would be playing the pipes, I said simply, "Oh, I wouldn't do that to you." (My pipe playing is quite bad.)