Sinking JBL?

If you want the gun to float with the shaft in, I bet you could do what I did with one of my Wongs. It started as a regular hybrid years ago, but when he started making magnum hybrids, I sent it back for him to add some lead and wood to the butt. He forgot that I was going to be attaching a reel and didn't account for the extra weight, so it ended up barely floating in a vertical position with the shaft out.

I went down to West Marine and bought a strip of teak- I think its about 1" square. I cut some pieces to a length that I thought would do it, attached them to the gun with rubber bands, and threw it off the dock to see if it would float horizontally. When I confirmed that I had the right amount of teak, I cut a bevel on the ends to make them look nicer, screwed them to the gun, and spray pointed them black to match the gun. I have almost no wood working skills or tools, but even I was able to handle this, and I bet those strips of teak from West Marine would work for you too.