I think your plan sounds solid, if a little on the safe side. My $0.02 USD is if it's a country wedding with camping and it's also a young crowd, don't feel like you need to play it conservative if that's not really you. Granted, I'm in a laid back and reasonably cool market in the US, but I've had clients and families from Canada, England, Australia, Jamaica, Mexico, Serbia, India, Africa, Lebanon, Thailand, Vietnam, Egypt, and probably a few more I'm forgetting, and I have found this to be universally true.

My wife and I photograph weddings so I go to a lot of them every year, always in a kilt. I do either solid black or one of several tartans. I generally wear a black vest, but always go for a shirt in a rich color rather than white, as well as a fun tie. I have several plaids, some stripes, paisley, and a funky pink and white and black swirly design. I usually do lovat green or blue hose, scrunched with Doc Martens, but I have some stripey socks that are cool too.