Malcolm,
This comes down to a decision about time. The best way is probobly to start over, but I don't think you have to.

If it was me, I might consider cutting wood bracing out of 1.25x1.25 to put in between the forms where things are bent. And use a driver drill to screw them in. I'd suggest using 6 pieces on the hull and then 6 on the deck. What ever you do use even numbers of sticks and put them in in matching sets. I'd use hard wood if I could find some in the right sizes From each side pre drill the screw holes You could use thes to torque the strong back back into alignment and the baot with it. Then splint the beam. Use shims to fine tune it until everything matches your string lines.

Another thought get some swingset anchors and put them on your sawhourse cradles

Good luck !RUSS