Well...since I wear the same tartan-kilt, I have worn it to 2 weddings in the past year. At my daughters wedding I was formal dressed minus the PC jacket. It was a August wedding outside with barely any shade. I had on a white dress shirt and a dark charcoal waist coat with a formal sporran, white hose and ghillies. The other wedding was "casual". Instead of wearing a Lovat green Jacobite shirt I found a dress shirt that was close to the same color with no vest and wore my regular leather sporran. Lovat green hose and shoes. I have found that wearing the Crawford modern means never wear any maroon colored shirts or hose, that to me looks awful. However, darker greens, grays (dark and light) and off white does well. Black (or charcoal) is OK too, just not sure if that is OK for weddings.

I would definitely ask the bride what she may consider "too much" and what exactly is "casual" in her mind. I have also been told that no matter how grand and formal or casual a wedding is, the "only guy in the kilt there" will get noticed.