Hey Mike,

I'm a new member, not as astute in fly fishing wiles as some of the salty dogs that haunt FAOL, but I've been playing with something for a few years that fits right in to your question.
I've been using a lanyard that carries my tools, tippets and a small boxt of flies.
It takes some thinking ahead, or maybe thinking back to how much of the stuff I carried in my vest the last trip out did I really use.
There's usually a pocket in a shirt or something to carry a an "extra or two".
Might not be something you're interested in but, depending on the outing, it might be a consideration.
Good Luck.