Okay let me get this straight, you want to dive nude and you are trying to figure out how to pee in the ocean and yet you have water coming from your nose. Hummmm, only kidding : ) it has happened to my husband, after diving and then taking a warm shower it appears as if the warm shower opened up his sinus cavities and caused the water to run out that he got trapped in the cavities while diving. He is fine and was fine right afterwards. Do not worry too much, just stay aware of things like that. I guess if a thing concerns you enough then seek medical advise.
Eve