I have one waiting in the box too. I have been flying both float planes and a copy of an Ace Seamaster for the the last couple of years and have learned the following.
Water gets into EVERY THING and gets ALL of the balsa wet. Nomatter how well you think you sealed all the iron on covering. I plan to completely dope/ seal all of the INSIDE of the Sealane before I cover it.
Consider 1/64th or thinner ply on the bottom of the hull instead of fiberglass. Gives a much smoother surface to work with.
I lost the Seamaster on a full stall landing in water when the 'smak' against the waves punched through the flat section of the hull aft of the step. Weird to see your plane sink up to the wing root as it taxis up to the beach.
Good luck on the build