Been reading the hybird thread and I have a question regarding construction. I see a lot of different angles on the sides but I am wondering...can the sides of the boat go straight up? For instance, if the bottom of the boat was 3' wide, and I wanted the top of the cockpit to be 18" high, could I simply go up on a square, like a box? I hope I'm asking that right and it's not too confusing. Thanks.