So I don't always use this system, depends on the shooting I'm doing but I dig it. I happened upon it by chance... I had purchased a UKPro Pole, 54HD, a nice floating 54" pole, so I had that laying around. One day while putt'n around I realized that the handle of the pole fit great inside of NRS frame tubing. I had some random tubing sitting around and simply cut a length of tubing long enough to accept a Lo-Pro and the length of the handle, maybe 7" or so. It works great. One can mount it anywhere on the frame. And one handy thing is you can simply grab the pole and pull it right out at will for a run up the beach or what have you. The one down side is that with the pole removed you have this 7" pipe sticking up vertically which could pose a hazard if fallen upon. Not much more of a hazard then falling on your oar stands but still... If kids are running around... you get the drift. I don't use it in big water, the GoPro is on on the helmet for that. I kind of found a home for it on the frame so when it's not in use I just losing the Lo-Pro and roll it horizontally. It looks clean and holds the pole well.
You get the idea anyhow, probably could be done with PVC and a Lo-Pro too. Basically just mounting ones "camera pole" to the boat instead of making your own telescoping rig. If that didn't help then I hope it sparked some other idea for ya.
If 54" above the frame doesn't clear your Bimini you can simply make the pipe holding the pole a little longer. Or what about GoPro's bar clamp gizmo clamped to the Bimini frame? I don't know...
Here's a link to the UKPro Pole I am talking about ::
UKPro POLE 54HDF
Cheers for now!