How do you get to the servo horn screw....through a hole drilled through the fuse (which can't be good on such a thin profile) or is it off center?

I'd also stay away from micros such as the 81. I've used 225s with good results, but you'll need to use the metal gears seeing that the control surfaces are huge and gears easily strip (on tail touches and the rudder or aileron taps the ground, etc). I've stripped three 225s on my Pen Knifes...either use standard servos or 225s (or the like) with metal gears.

Using one or two servos is completely up to you. Looks good with the one setup, although I've never tried it on the Pen Knife. (Thanks Paul for posting that pict.)

-Juhan