Steering????
No steering on floats my friend. The front wheels caster.
If you put steering on a set of floats, you would trip the aircraft on 99% of all tera firma landings.
The real thing steers with brakes and rudder input.
Most RC aircraft have enough rudder input that brakes are not needed.
I could turn my old Goldberg eagle on about 6 foot circles with the floats. That was better than with the nose wheel.
One thing to remember is that it takes practice to get it just right.
Castering wheels are a bit slow to start, and come out of a turn the same way. Once in a turn though, they are very nimble.
Putting a turning limiter on the front wheels is a good idea. This keeps them from turning far enough to cause the plane to trip if they are full over.
Look at the drawings I posted earlier. They will explain how it all works prety well.
Peter