A great starting point. If you're interested in improving the design, I'd consider moving everything aft about a foot (maybe not even that much) so that the bow rides higher. Your rudder could be wider as well, giving you a little more control at the slower speeds you're traveling. Additionally, I think a larger prop or a 3-blade prop would give you better performance. It doesn't sound like the motor is being worked very hard here, but I'm no expert on little gas powered aircraft engines.