Thank you all for your advice so far. That's good stuff to know!

I hastily put these on last night to try to get some pictures before dusk while the light was still good. I don't have a bowtie, so I just wore a regular black tie for photo purposes. My wife, by the way, LOVES this jacket with the kilt. And I actually think it looks pretty good too, even with the regular tie. It doesn't look nearly as formal as I thought it would. Not like a PC, anyway. I suppose that's because of my tie choice and the fact that my sporran doesn't have a cantle.



I also tried it with a regular black day sporran, but I don't think I like it as much:



And here's the white jacket:



Last but not least, here's a close-up of the buttons. They are indeed military. That is the USAF logo. My grandfather was a full-bird Colonel, and was head of the Alaskan Air Command as well as the Strategic Air Command, among other roles.



So I will probably need to replace the buttons with something civilian, which is easily enough done. I'd rather not permanently alter the jacket by cutting off the shoulder board loops, though, unless it's absolutely necessary. What do you think? Would it be a fashion faux pas to keep the loops on the shoulders?

You posted in the Traditional forum, so I assume you want traditional advice. You can dress down your kilt outfit with your hose and sporran and shoes as easily as you can with the jacket. It IS a "dress mess" as in FULL dress, but this is a wedding- and you are a sharp dressed man in a kilt.
Yes indeed, I am wanting traditional advice. I may intentionally stray slightly from tradition for this wedding, since I'll be the only kiltie there, but I at least want to learn the rules of wearing a mess jacket before deciding whether to break them.

One of the oft overlooked rules of wedding attire is that as a matter of mutual respect both the bride's family, and that of the groom, should be dressed to the same level of formality. That being the case it would be absolutely correct to wear a mess jacket with your kilt, provided you replaced the buttons and removed the shoulder board loops. However, before committing to wearing the mess jacket, make sure that it is long enough to cover the top of your kilt, with no shirt showing on the sides or back.
That's a very good point, and I hadn't thought of that. I'm told he's wearing his USAF dress blues, which is dressy but not overly formal, as I recall.

Do you think this mess jacket is long enough in the back and sides, based on the picture above? It seems to have at least an inch or two covering the top of my kilt and part of the belt.

So after a little net research, I came across what sounds like a picture of your jacket here, about a third of the way down the page.
Yes, that is it exactly!