With regard to the beams, I suggest that you play with the idea of making them yourself.

I've made superstrong beams for my 15 ft homebuilt epoxy sea-cat. I laminated them also fixed to the hulls, which is the most weight saving way. If you are interested I can show you a photo of the build up of these beams. They are made of wooden hollow core and a very strong carbon skin. No dolphin striker was needed, they are 2.60 meter.