I'm of the opinion that it doesn't hurt to get the tag, then you'll have it if you need it. Some may recognize the Convaid Rodeo as a wheelchair and you won't be questioned; however there could be a CM who sees it more as a stroller, especially if your daughter is young (a 30-yr-old may be more recognizable as using a wheelchair than a 7-yr old). The last thing I'd want is to be at the far end of a park and run across a CM who insists on the stroller tag; you'd have to walk all the way back to the front and waste precious time in the park that day. If you want to take the chance, see how it works the first day without a tag, especially if you won't mind an extra run back to Guest Relations or are willing to skip any given ride that day because you'll be returning later in the week.
Enjoy your vacation!