I dunno - I haven't heard much about people raping each other at nudist camps. They seem perfectly capable of not attacking every sexually attractive naked body they see..? I mean, that's a lot of naked body parts out there for the eye to see, and yet, these people manage to get on wonderfully.
Sure, I can see where there'd be discomfort, but if you can't control yourself, then you have a serious problem on your hands. To tell you the truth, I've seen sufficient naked men in my lifetime that the sight of a penis doesn't really do anything for me - it's just there. At worst, I might start laughing just because it looks so silly just dangling there.
Of course, it doesn't help that I work in an animal clinic, where all you see all day are male bits dangling, and have to, with a straight face, explain what neutering is. I mean, literally, I had to explain to this guy over the phone that neutering meant removing the male testicles. Five times, no less, with a client standing there laughing like a lunatic. I was like,
"Must. Not. Laugh."