ORIGINAL: JimCasey
Here's my logic. It has worked for me.
I put the WR on the left float.
If the WR is making any drag in the water it will be necessary to add right rudder to counteract the left drag.
It's frequently necessary to add a jab of right rudder anyway just after takeoff, so you're already there and not crossed-up.
Seems counter-productive... If you are concerned with needing to add right rudder (p-factor, torque, etc...) it would make more sense to put the drag on the same side to which you add rudder deflection during TO roll (or float?). By placing the rudder on the left, you're simply increasing the amount of left yaw tendency to the aircraft, hence, requiring even more right rudder.
Right side mounting increases drag to the right, thereby decreasing the amount of right rudder required during the TO roll.
Just my $.02.