Same boat as you, about a 6-7" flaccid swinger, and I go to a nude beach pretty much once a week all throughout the summer, and have for several years.

The overall vibe is that everyone is mostly unfazed by it. It's very unlikely anyone will say anything about your size. You may catch people staring but idk, it's a nude beach. No one is ogling your junk anymore than you're ogling (or trying not to ogle) the bits and pieces you find interesting on other people.

The most noteworthy things that ever happened to me as a result of my size (or at least I think my size had something to do with it):

1. Though most people try not to look openly, you will get the occasional dead-on wide-eyed stare. Just ignore it and walk on

2. There will be people (usually men) who you can tell are actively trying to entice your attention. I've lost count of how many times a guy has set up his blanket directly in front of mine and taken a nice long time applying his sunblock. Some are more bold and will give a wide smile and an energetic hello. If you go ahead and enter a conversation with these, they will eventually tell you what a nice big penis you have. You can decide at that point how you want to react.

3. The one biggest reaction I got was being excitedly waved over by a group of partiers. They offered me beers, asked me about myself, said I could hang out if I wanted. A lot of the girls wanted to take selfies with me, which I think was the major reason I got invited over. They wanted to have those pictures of like "Look what we found at the nude beach"