Ok, so the final design wasn't completely "final". Since that last post, we have simplified the design by removing one bevel box and adding a U-joint. This more evenly distributes the angles among the joints. It should provide for a smoother steering action. Also, removal of a bevel box and addition of a U-joint should reduce the net cost.
Side view - Updated steering plan
The update involves moving the main reduction gear closer to the rudder post, which makes for more compact space utilization. A couple aluminum brackets to mount the U-joint flange bearings will be needed (fabrication should be simple).