Here’s the trailer. Clara Hopf’s face can be spotted at 2’55 (don’t know if she’s the girl in the nudity scene, I’ll have to check that more meticulously)
The film is even in Giusti’s book (must have overlooked it yesterday)
IMDB and the (title of) the movie’s thread mention Stelvio Massi as director, the database and Italo-West-Fan’s text list Bianco Manini (Newman Rostel). Giusti also thinks Manini directed the movie, but he quotes Rick Boyd, who sustains that he was directed by Alberto de Martino (Martino denied this)
Bizarre. Giusti also confirms that Hopf became a make up artist after a very brief career as an actress. Bizarre career move.
He also confirms that Kinski can be spotted in one scene. I’d say the train scene in this trailer is taken from A Bullet for the General.