Those planking screws look ok if you are fixing longitudinal planks, and have nice thick frames to screw into. In my case they would have to screw into my very thin Stringers, which wouldn't be strong enough. So i will stick with the G-Clamps i think.
2 things i have learned so far, 1) i need a lot more clamps, and 2) i must soak the planks in hot water for a few minutes, otherwise they won't take the bend, and will snap.
Once my new clamps (from ebay) arrive, i can plank both sides simultaneously. Which might mean i get the first layer finished before Christmas