I've done the gopro thing ... and am at the point that unless conditions are freakishly awesome, or a novel spot, am kinda over it.
Helmet mount is easy and out of the way, but the extreme fisheye flattens surf so much that you'll be bummed....that "head high" wave looks waist high at best. (Plus, if you get lucky enough to actually have someone taking pics from the beach, the nerd factor of that camera on your head means you will not be in their viewfinder

)
Strut mount is fun, like having drone footage, can see the scenery. Also nicely out of the way.
I have a line mount but haven't experimented with it much yet. A friend using one said it's effect on kite performance is noticeable, in underpowered conditions. I also don't like potential to interfere with lines or safety system (filming yourself is fun and all, but not if it potentially screws up that epic session).
You can put gopro on a selfie stick, hold it along bar then once in a good spot, pull it out and film yourself as long as you can fly one-handed. I tried to do this in 30kt gusty winds though and just about pulled my arm out of its socket. You can also stick the selfie stick inside wetsuit back or impact vest, and get the looking down angle.
A gopro rule to follow: do a quick edit of your footage within 24 hours or consider it gone forever, you'll never want to watch it later! What I do is a quick skim through first and make notes of the times for shots want to save. Then do a quick rough edit. I used windows movie maker but found it had hassles with file formats....so I bought corel video studio, pretty cheap, works well. There's lots of good programs out there, should be easy to use. I hear iMovie is good.
Two strategies for editing: 1) hoping people might actually watch it: short shots, varied angles, only the highlights, under 2 minutes, preferably under 1:30. or 2) assume you are the only person who will ever watch it all the way through, keep all the long shots you like, and know that you'll like the coolest oldie in the home some day.
Another gopro rule: go buy the cheapest big external hard drive you can find. You will find out quickly why new hard drives are now in TERAbytes.