for the downhaul I would strongly recommend clamcleat cl257;
We have used this for over 10 years and find it preferable to elastic which is prone to allow the rudder blade rise up slightly when beating in a seaway.
And we don’t bother with an uphaul – if the boat is in the water then the rudder blade will float up on it’s own, and if the boat is out of the water (or about to come out) then take the rudder off. that way it will not get damaged.
We have always used wooden rudder stocks, they look more substantial than the metal ones and over the decades they have had a more thorough testing.