I too just use the largest Zoo Med or Exo Terra water dishes for my snakes. I have never seen any of my snakes soak ever except my sunglow soaked for almost a full day when I got her because she was shipped to me just out of blue and the stress combined with low humidity and shipping screwed her shed up. So I guess she knew she had to soak to get the old shed off which combined with my help came off fine. Since then I've never seen her go into her water dish either. I do catch all my snakes drinking though. But as Anna said, I would use a wide plastic Tupperware container if your BP does actually like to soak. Have you made sure he doesn't have mites as snakes that have mites will usually soak a lot to try and relieve themselves. Or they will sometimes soak if the ambient temp is too hot, sort of a way to cool off.
Nope ^^ he checks out great. He doesn't soak a lot maybe once or twice a week. If I set him in a bin of water he will settle in it. Maybe he's just being a goof