Andreas,
After stumbling over the tiller pilot and having it exposed to the elements, I mounted it internally.
It is mounted on a piece of 1" x 4" piece of hardwood with brackets; only the tip of the actuator protruds when in the stowed position. The 1" x 4" is set at 90 degrees to the tiller/boat and is fastened in with screws and glass.
To connect to the tiller, which works through an arc, I made a link from 1/8 " stainless sheet stock. The link is 1" wide and approximately 10" long. At the acutator end of the link is a 1/4 pin, welded in place, that fits through a hole drilled though the plastic cap At the tiller end is a quick disconnect pin for emergencies. The travel of the tiller on my installation is about 60 degrees to either side of center. Of course this will vary with the distance from the rudder post.
I regularly used this installation during both tacking and jibing. The only difficulty I encountered was the rendency for the the tiller to rise during course changes. This was an easy fix, drilled through the tiller brackets and installed a quick disconnect pin that is only in use while operating the auto-pilot.
If you are interested, I will send you photos, measurements, etc.
Reagards,
Dan Sullivan (Acqua di Vita)