LOT'S of torsional stiffness was lost by cutting away the cap, bulkheads and inner liner. (Try twisting a shoe box with and without the lid taped to it!) If you don't want the boat to be as flexible as a wet noodle, I'd strongly advise laminating some 1/2" balsa core to the hull sides! A good stiff cap glassed to the hull will also help. Since you want to use a lot of composites, I'd suggest you check out
Dave Pasco's article on core materials.
And it would be a good idea to keep that anchor locker, which will allow you to use a big oval hawse pipe and mount anchor on deck. There are situations where being able to quickly deploy an anchor can be a big safety factor, or at least very handy if you're trying to anchor over a hot lobster spot!