I may not have an answer, but I thank you for posting this. So far, I haven't made all that much in the way of mistakes in my build, and I typically have at least one "Doh" moment in most of my projects. I might admit to having a nightmare about trimming the skin short, and having to tell my wife that I need to not only order more fabric, but that I'd have to resew the entire 'yak, too. Her kayak build won't start until mine's finished, so...

I've ran across threads mentioning folks taking a dart out of the fabric to deal with complex curves or wrinkles. Logically, a patch of fabric ain't much more than two dart cuts. since you're still joining fabric to fabric. I don't see why you couldn't do it. But just 'cause it makes sense to me doesn't make it so.