Interesting. Despite perhaps seeming a bit clumsy and excessive in execution, that's actually a pretty clever concept. The leeboard-bracket-like attachment system would allow a secure, clamp-on and detachable rudder system without having to drill any holes in the stem or permanently attach any rudder hardware there. If you made the bracket with some beam adjustment, you could even use the fore and aft placement of the bracket to fine tune the rig balance with relation to the sailplan's center of effort. I suspect that a bit of careful slimming-down of some of the components might make a pretty substantial reduction in the system's weight without compromising too much strength. A couple of longer, narrower, higher-aspect rudder blades with a little shape would probably also improve performance. Yes, it's a bit outside the box, but I kind of like it.