I love the toolbelt idea, thank you so much! I had a few odds and ends for her (a retractable telescope in a holster, a pocket compass, magnifying glass, etc. - plus would need stuff like my cellphone, cash and camera

- that this would be perfect for! The antennae idea is so cute, too.
I was thinking a parasol might be cute, but a walking cane might be better for Carmen. And I already know I'm going to be melting with at least 2 of my costumes this year. I won't be wearing anything under the trenchcoat up top, since it buttons fairly high, so that should help. It's not that heavy, but it is indeed a lightweight wool coat and a hat. At least I won't have a wig with this one.
My main issue right now, aside from my total accessorizing!fail, is the color scheme. I think she might be more "recognizable" with a gold scarf and gold/yellow accents in the hat instead of black. (But the black is sooo pretty...) Also still deciding between the more Edwardian riding pants vs. a big full Victorian skirt. (I have both.) Thanks again for all the feedback and ideas!