Have you tried the exterior nose pincher that seals the nose closed for swimmers ? I have a friend who's problem sound similar to yours and he uses this for surfing with great results, no water in his sinuses.
I've taken cold water Sex Wax and blended it with cotton in a pinch, worked very well actually.
Sam
I've taken cold water Sex Wax and blended it with cotton in a pinch, worked very well actually.
Sam