Back in the day shots from the movie were actually featured in Playboy. Not that I would have ever looked myself. No. Certainly not.
I simply heard about them.
And, of course, the nudity in the film is really immaterial. It's the plot all the way!
But seriously, DoD is a very interesting film. And it would still be interesting without the nudity. Though no one could say that the nudity hurts the film.
Here's the ad (which I don't think I've ever shared) that appeared in the Boston newspapers on August 4, 1971 (the same day NoDS opened):
Karlen also did an interview with the long defunct Boston Sunday Advertiser that became infamous in fandom in the '70s because many DS fans believed he said working on DS was working on "garbage." I have shared that interview before - but it was back in the VantageNet incarnation of the forum, so it's no longer available. But if there's interest to see it again, I'll try to dig it up...