This is quite an interesting question. Personally I'm not sure what to do. A while ago I aquired an old Atoms which seems to be a well designed product (I'm sure Eric could comment on it). It's based on the servo pendulum principle and used to be very popular with french sailors. Unfortunately production ended in the early nineties and my kit needs a rebuild. I guess it could be done using off the shelf parts like carburettor linkages etc.
The nice thing about the Atoms is that it's very lightweight and comes with a remote control line wich uses a worm gear on the vane section.

What got me thinking however is that my Benford 30 has a transom hung rudder which would easily lend itself to a trim tab.
Since these can be very effective when correctly designed and since my Atoms is in need of a rebuild anyway I'm playing with the idea of converting it to a trim tab. Instead of driving an auxiliary rudder and running lines to the tiller the windvane would directly work on the trim tab.
Peter Foehrman criticises the trim tab design of now being quite dated and outmoded by far superior products like his current Windpilot but to be honest that sounds like good marketing.

Comments appreciated!