My Engine

[Dormouse]

A Kort nozzle on it's own does not protect the rudder. But the double rear skeg I mentioned might lend itself to allow both. I will have a little think.

[XUD Marine]

This shows the exposure of the prop and rudder.

For a skeg I was thinking of maybe something that starts as a bit of channel bolted through the keel, extending back under the rudder.
It would then need some support at the back to keep it from bending up to hit the stern gear if it did ever get an impact. Probably V shaped supports. I suppose a kort nozzle sat on top of the skeg, top fixed to the hull, would give some support. Of course a normall skeg would have a lower bearing for the rudder shaft, but here the rudder just hangs on its shaft. It just feels a bit vulnerable to me, if you ever grounded on something hard.

[Dormouse]

A bolt on skeg rail with a dipping tail under the rudder and 2 V brackets fore and aft of the prop might give you the protection and strength you want.

How wide is your keel at the bottom?

[Dormouse]

The chine rail boards I talked about looked like this.