I bought a Quik Pod Sport pole years ago. It allows 90 degrees of rotation in each direction providing a full 180 degrees of motion. However, we quickly discovered the results of cantilevering a GoPro from a beam were unacceptable and ditched the pole. Stability will only get worse if you add a light, but I am sure there will be others that disagree.
Getting stable underwater video is difficult at best. For what it’s worth, I recommend getting an aluminum “V” tray (Snake River Prototyping, Beneath the Surface or something similar) and a pair of good video lights when possible. In Bonaire a few weeks ago my buddy was photographing a Sailfin Blenny, so out of boredom I zeroed in on a flounder. The fish kept swimming faster and faster and faster over the sand. The 30 second video looks like the camera was glued to him. I wouldn’t have been able to do that with a GoPro on a pole.
