Try again. And again. And again.
I waited to put her in this time until after she was fed, changed, and basically passed out in her stroller. She fussed for about 1 minute, and then I spent 10 minutes walking her up and down my front yard outside (as suggested!) It’s literally about 104 degrees here today, so I can’t be outside with her in the wrap for very long, but she fell asleep in it, and has remained in it for a good 20 minutes! A record!
I’m still not 100% confident that she will always be this good, but we’ll keep trying.