Actually Roger Ebert has written 2 other movies for Russ Meyer (using a pseudonym) both of them also rated X (and more explicit than Beyond the Valley of the Dolls). The titles are
Up! and
Beneath The Valley Of The Ultravixens (I heard that Roger's wife is "Junkyard Sal" from ...Ultravixens and that she was an escort when Russ introduced her to Roger).