Kind of a random topic, but there are often laws banning public nudity. Presumably even nudity that can be seen in public, but which takes place on private property (say someone is showering or sunbathing in the nude outside).
How would this issue be dealt with in ancapistan or under a "free" government?
Is it a violation of NAP?
Yes => it is not allowed
No => then it depends on the property owner
Most property owners are influenced by what their customers want. If most people are grossed out by nudity then most places will ban it. But as long as there are some nudists around then the incentive will exist to establish nudist friendly places to capture their market share. So everybody wins.