I took apart an electronic toothbrush.
It occurred to me that the replaceable tips
contain a knee-joint. the brush rotates from
-45deg to +45 deg, which is enough for us.
That means that these small tips can be used to
link up with rudders in tight places (VIIc, for instance).
Since they take in rotation, the normal pushrod action
needs to be converted to rotary action. This should be
simple (same o-ring will do the job),
and it is less sensitive to play by not bending while pushing.
Did not use it myself, but is seemed quite usable.