You designing good looking plane. I have one question. Are you concerned that without any deflection plates or the sponsons, on takeoff the water will be sucked into the prop.
Original Shearwater had this unique shaped fuselage that shielded the prop, but at the cost. The drag from that area on other vice clean design made the plane un-economical. The Shearwater company abandoned that version and is in process of working on new, much cleaner design. I wish them and you all the best with the planes.
Despite of that, I love flying my R/C version of original Shearwater. Here is the vidio with my model flying.