Hi Paul,
welcome to the Berlin Grunewald Lauftreff

Our group exists since 6 years, and we are about 4-10 people which regularly run naked every Wednesday. Some even do it in weather conditions that make me shiver with cold...

I myself have the luxury of being able to run naked in the woods whenever I want to (which is always). So far, I have never experienced any problems, quite the contrary, most people I meet are very friendly and sometimes wear a big smile on their face, some few people ignore me. A couple of times I was asked why I do this, I usually explain, because it's just great, and suggest they should try to experience it themselves, which is always met with huge laughter...
I am not too much into hiking, mainly because I don't like a backpack on my skin, but did it a couple of times, once even in the mountains, and it was always a great experience...
Marc