I have successfully mounted a Go-Pro on the strut of a high wing aircraft using the helmet mount which uses straps. There's no shake or wobble at all up to 150 knots. But when it faces forward, you only get about ten minutes of useful footage before fly splats, atmospheric moisture and general pollution smears the lens.
I know people have use the suction mount to attach Go-Pros to glider wings. The smooth surface and lower speed makes this work. However, remember that the suction mount works on differential pressure and as you climb that will reduce. They have come off!