I have flown a real nice 40 ARF that adapted well to floats. There is a smaller electric version that I believe would fit your bill of a electric sport plane on floats. It would be the Mini Pulse XT ARF from Horizon. You will need to pick up the proper size foam floats but I can personally tell you the 40 size Pulse with an OS 46 make a great flying, super fun, aerobatic float plane. I would think the Mini version in electric would do the same. Just my opinion. Horizon link below.

http://www.horizonhobby.com/products...xt-arf-EFL2375