A little late with this, but I always have thought about doing a Shavrov Sh2 flying boat. It is a smaller Soviet amphibian from between the wars. It was also used in Finland, and there were ambulance versions with different color schemes too. Looks like it would be fairly simple to build. I would have to make mine electric, though, as I fly at sunrise in front of a bunch of million dollar homes!

Good luck,
Dave