I sure will post them here!
I've been struck by a touch of creativity and solved the rudder problem:

Since the hull parts were allready glued together and sealed by filler, I had to improvise.

This is the result.

And finished.
I drilled through the rudder assembly from one side with a long drill and managed to keep the path straight and so I could insert the rod and keep it movable.
I attached one of the rudders to the rod before I inserted it and as the edge stuck out at the other side I glued the other rudder in place with super glue.
I am tempted to try that with the fairwater planes but my drillings would have to be even more precise.