The truth of the matter is that sometimes I cannot be posing in full nudity. I often shoot in public spaces, or my hotel windows are too close to the ground floor, or buildings across the street, where others could see me... to avoid getting into trouble. I wear something called a C-Thong. its shape like a C and has a metal "arm" that allows it to stay in place, despite moving around.
These items come in different colors and patterns. The nude color was not as useful as one would imagine because the mesh is transparent. It defeats the purpose of having one.
You can google them, or buy them on Amazon...