Actually, you cannot use a wire to the rudder type tailwheel. The rudder does not extend beyond the elevator, and unless you hack the elevator into two pieces, you won't be able to get one of the springs/wires up to it..

Mounting the servo is an option, but where woud you put it? You don't have access to the back end of the fuse, unless you want to start cutting covering, and putting the servo in the center of the fuse (where the rest are) would be a trick to get a pushrod back that would work... The only option is the pull pull, and to tell you the truth, unless you have a ton of time to fiddle with it versus fly it, forget about it, it's not really worth the trouble..

Now, free floating, there is a good idea..