You are going to find this funny but I strap it to my ankle and not the board when I want one of those shots. I use a long piece of parachute rope and lash the thing on. It works really well.
My buddy had the surfboard attachment on his board and it popped off the first day of use. Plus the video was very shaky because of the board chatter. Straping it to your ankle relieves all board chatter shake and is pretty stable.
Sometimes the best solution it to go low tech!
Here's a video I made that shows those views.