Per Michael Daly:
To get the weeds to clear on the fixed part, there's going to have to be some
sort of sweep angle down that won't catch the weeds.

I think I've got that already. It's just the gap between the front of the
rudder and the bottom of the hull that opens up when the rudder is turned -
courtesy of the hull's vee.

Never thought about the post-as-leading-edge thing with something fixed/angled
in front of it. That seems like the Good-Right-And-Holy path to me....and if I
were ordering this kayak again, I'd ask for a little thruster fin box to be
installed there and have a rudder made as described...
--
PeteCresswell