ORIGINAL: Jomamma
Just an idea, never flown with floats or seen anyone do it for that matter, but with a trike gear could you just attach a piece of wood to the nose gear and use it as a rudder? would a rudder work in front? i dunno, it probably wouldn't work
the problem with this is it would tend to "trip" the aircraft. you could all too easily flip the plane.
You can make a linkage that is driven by the nosewheel strut to turn the "water rudder" though. (the little rdder (or rudders) on the back of the floats.)