Mounting your GoPro camera to your surfboard is the logical approach. This keeps your hands free, but seriously limits your extreme downhill experience to a single angle. If you want to keep a different camera stabilized, consider the Gary Fong flip cage review instead.
The GoPole Evo extends the GoPro camera beyond your reach by 26″ and lets you capture your footage from a myriad of angles that otherwise would only be achievable with multiple takes. And even better, the pole itself is “transparent” so you won’t end up with a metal “stick” in your shot. Now your best GoPro can come along with you everywhere you go.
Moreover, a 100% waterproof design means that it is capable of diving as deep as 200ft. And if you happen to lose your grip it will float the camera back to the surface. Lastly, the head can swivel, though I believe it is limited to 180 degrees.
GoPole, the manufacturer, says that it attaches to all versions of the GoPro camera, and weighs only 4oz. You can grab a GoPole Evo for $40.