Another thing to try is to mount the tailwheel a little forward of the rudder post area, let the shaft of the tailwheel extend up into the fuse, add a control arm to it and run a control rod to the other side of the servo arm. You might have to cut an access panel in the bottom of the fuse, but you can mount the tailwheel in the access panel (sort of like putting the aileron servos on the panel that holds them in the wing). Doing it this way allows you to adjust the tailwheel for more or less travel to make your taxi turns tighter or wider.