Great suggestions for bags/vests, etc. Don't think I could carry off the "hairy tummy" one, LOL
The main instructor with Cassie's obedience classes gives me a hard time, if I keep a larger fanny pack with me and sling it over my shoulder. I've taken to packing things in a reusable shopping bag, that I set by the sidelines. If I have pockets, I put treats in pockets during class. If I don't want to wear a fanny pack around my waist, I'll sometimes use a very tiny purse that I wear messenger bag style.
A couple of things I like to keep close at hand (to accompany the poop bag): a disposable rubber glove or two, a hand wipe or two and a paper towel. I'm always glad I have these items for a messy poop event.