How do you want the inside of the boat set up?
There's other places to put foam aside from a seat. Some put it in the floor, some put it in the sides, some do both. I believe Coast Guard requires boat to be neutrally buoyant but I could be wrong on that. A semi v will run and ride a little better than a flat boat, flat boat will get skinnier, its all a tradeoff.
Have a look a the Havoc 1650
I love the way this one is set up