Not to mention the massive bulges of those floats are going to create drag down below the center of mads while all the thrust appears to be well above the cente

Not to mention the massive bulges of those floats are going to create drag down below the center of mads while all the thrust appears to be well above the center of mass. This is going cause the aircraft to pitch want to pitch down and give it some negative flight characteristics (especially without the leverage of a proportionally long tail to help counteract those forces.