Surfing Waves

Is the Dummy mount for the gopro heavy for your jaw after a while? Any of youe try it before?

There's a chap on YouTube 'BenBrown' and he just chows down on the floaty back door, seems to work for him!

The mouth piece GoPro thing seems a fairly reasonable way, if it has a leash so in a wipeout you can spit it away from your face. ( there have been facial injuries and teeth lost)
Please do not consider either a soft baseball cap type mount or a head band mount.
The hard casing would do severe damage to your skull and brain in a face plant.

There is another option which is a Gath helmet with solid peak with a mount upon that , might be a little harder to operate pushing the buttons , but it is point of view with a solid protection between to camera and brain.
Congratulations in not just going for the boring front of board mount.
POV equivalent of bad dancing under a shower.

I don't know about the Dummy Mounts, but our mouth mounts are only 1.4oz http://hostevie.com/shop/gopro-mouth-mount.html

It's more the weight of the GoPro that matters. 1-2 hours isn't bad, but anything longer can get tiring.