I clamped a large scrap peice of ply in place at the forward frame/stem to make sure that it would all sit nicely.
Next I have to glue and screw them the battens in place.
I have a tiny block and tackle in place to pull down the front of the battens. I've clamped some offcuts to them, so that I can pull them down from one side, to introduce some twist as well as bend into them. This will make it a whole lot easier to bend the front of the ply.
I'm not entirely sure how I find the battens when the bottom plywood is in place, so that I can locate the screws. Any thoughts / detailed photos would be welcome.