A pair of friends are getting married in a few months, and I've been both invited as an attendee (but not in the wedding party), and permitted to wear a kilt by those getting married (with one spouse-to-be inquiring about kilt options for the other spouse, but that's not the target of my question, here).

I'm wondering what to wear. The style of wear being asked for is, "cocktail" attire. From knowing and talking with the couple, this isn't quite black tie (but I suspect such would be ok), but isn't as informal as t-shirt wear either. If anything, it's at least a bit more formal than typical business-casual.

I am fortunate enough to have some options for kilt wear, including, but not limited to:
- a few jackets meant for kilt wear, including a black, Argyle jacket, plus a few other jackets in non-black tweeds.
- a few higher-end vests, one in black (which was sold with the black, Argyle jacket), and the rest are (mostly) shades of brown
- a few kilts in (universal) tartans, plus one in tweed
- at least one, fur sporran with a polished metal cantle, plus a few, leather, day sporrans
- lots of options for hose, including black and white, among other mostly-solid colors. I do, also, have a pair of red + black diced hose with plain, non-castellated, tops.
- ghillie brogues in both black and brown
- various dress shirts and ties

I'd like this to look good, but don't want to go too far out, and I want to leave out some of the more high-end, or outright costume-y type bits (such as frilly shirts or shoulder plaids, not that I find anything terribly wrong with those, though!).

Any suggestions? Thoughts? Tips? Critiques?

Have I, perhaps, answered my own question(s)?