I'd question your motives. Is it a lack of attention that has you wanting to expose yourself in public? Bc it turns you on? If so, that's a good way to end up with a record.
However, if you have a genuine desire to go clothes-free outdoors, bc it feels so good on your skin, freeing, relaxing, at one with Nature, etc. then that's a different story. Lots of people love being nude in a natural setting. Even those who don't usually strip off, have done so in the right environment. Look up Spencer Tunick's photography to see what I mean.
Genuine naturists aren't likely to indulge outdoor nudity just to jerk off or have sex. There's a big difference, so I'm just trying to clarify where you're coming from in your question.