> Retracting the rudder would require the bent upper arm (?) to be straight
> in line, therefore the rudder would not get jammed at an angle.

One of the advantages of the stern-mounted kick-up rudder is that if you paddle over shallow water, the rudder will swing up over any obstruction without damage no matter what the orientation as long as you are going forward. If your system needs to be straight to retract, you run the risk of it breaking off. You might want to make it strong enough that it won't break or flexible enough that it can absorb an impact.

The picture did not come through on my browser, probably because it is a BMP file instead of a GIF of JPEG.