The floats should be 18% to 25% of the wingspan wide. 18% is scale, 25% is sport. Take your pick of anything in between. The floats should be 75% of the length from prop washer to rearmost part of rudder. The step should be on or not more than a 1/4 inch behind the CG. The floats should be dead level to the horizontal stabilizer, not the wing. Follow these tips and you will have great success.