I was in a similar situation recently. The bride had commented that I should come to the wedding in a kilt before she asked me to be their photographer.

I certainly felt that I had permission to attend, and to photograph, in a kilt. But I chose to wear a suit in order to be as inconspicuous as possible, and when I took the time to explain that to the bride, she appreciated it.

By the way, I would have been the only one kilted. That too makes a difference.