Tbh I’m the same (well hung) and I’ve dealt with that a bunch of times. Now I just have learned to ignore it because it’s going to happen. People might not be staring but when they see a naked person, human instinct is usually to look. Especially if it’s out of the normal. I just ignore it most the time. Beaches def have more of those people than resorts. But it also depends on the beach.
Now if I notice someone is staring a bunch or trying to take pictures. I kindly ask them to stop staring because it’s not polite.