Michael, go for a bigger Kayak with some features of the Canoe and the Pirogue and some from a sailing skiff. You might even go for a larger beach cat design.
There are many free plans out there, some not very good. Some better.
20' to 30 foot' about 3 foot to 6 foot wide (unless a cat). A decked canoe is a great idea. The narrow bow of the pirogue allows you to get decent beam quickly and keep a narrower beam at first for some wave splitting action.
Check out:
http://www.sailingcatamarans.com/index.php/purchase-designs/beach-cats-and-dinghies, he also has small trailerable trimarans and catamarans.
Svenson's has an old and design for a really big 'surf board' sailer.
http://svensons.com/boat/?p=SailBoats/Manu
http://flo-mo.weebly.com/boat-design-studies.html
Here is a 'duck hunter'
http://www.gatorboats.com/duckhunter_photos.htm. I don't like the keel, or the lack of the keelson, but from the waterline up it looks like what you are talking about, modify the waterline chine and down, and you would have a much stronger boat, and I would lengthen it to about 19 to 22 feet. That would give you better load ability without being huge.
Maybe attach an ama like you would with a kayak.
But, I still like the idea of the Mana. Maybe combine some of those features with the duck? Use the Mana for the bottom and the Duck for the top?
Have fun.