Because I'm thinking about Harriet the Spy a lot this year, I recently re-read Suzuki Beane, a book (published in 1961) about a girl who lives on Bleecker Street with her too-cool-for school parents (Suzuki, unfortunately, DOES have to go to school). Written by Sandra Scoppettone, the book was illustrated by Louise Fitzhugh (you'll happily recognize the style). If you haven't experienced this book, find a way to read it. (It's always nice to be reminded that people bravely took children's books to unconventional places long before any of us were writing.) I found several places where the book is referred to as a satire of Elouise. I'm not convinced.
I also found this: