I read that The Fool were always going to be included to do something (if anything) on Peppers, But Fraser (a man who had many links in the underground art scene of the early sixties) disagreed with the Fool being a part of the whole peppers-project, but his advice was ignored, as Mccartney wanted the inner sleeve design to be specially created by the Fool.
I dont think the front sleeve was ever thought to be created by the Fool.