If you are interested in any of this read Legs McNeils book "The Other Hollywood". It's an excellent oral history of the porn business from the late '60's on. Legs is also in Sex: The Revolution and was a panelist at the screening. He's still a punk.
I met the Hart Perry, producer/director or Sex, who also filmed Hendrix at Woodstock. He did the nude and mud scenes as well. The best parts of the movie really.