I tried a Racelite Tiller Extension Swivel to connect the tiller extension to the offset rudder on my CLC NE Dory, and it worked GREAT in a 2-day sail this week, plus it is a much more positive attachment method than the original version of running a piece of line thru both pieces, rudder control is much more responsive.  You can see I rounded the end of the tiller extension so it can freely pivot or lift up when needed.  It is secured with 10-24 machine screws and cap nuts.  I was thinking about putting a quick release removable pin in the swivel but since my tiller is removable from the rudder, storage with the tiller and tiller extension still  connected is not a problem, besides a quick release pin is more likely to get caught on something and come out than the pin that came with the swivel.  

http://www.duckworksbbs.com/hardware/p-g/rl494/index.htm