Casper is 10, and for shoes we are firmly in the women's department (size 8). But while she is close to five feet tall, she is still built like a 10 year old - I happen to have measured her recently, and she's about 24-22-24. Adult clothes would swim on her still. (For comparison, J Crew's size 00 assumes a 34 inch hip.) I suppose I could try the "juniors" section of a department store, but then we are back into the "clothes styled for teenagers" problem.
I am honestly considering trying to talk her into boys' corduroy pants.