The GoPro is "large" and should not be in front of a control surface. Depending on the surface, suction cups work great. I would not like to use the tape stuck on mount on a glider finish.

Better use for external use on gliders are small flat,"key fob" sized cameras, low profile, use good double stick foam tape. They cannot normally be remotely controlled, turn it on before launch and forget it.

If you lose one in flight, it's only $10-$20 and ounces falling, not $400 and a half pound falling.
BillT