I agree with the 4*40 or 60. I just love my 40. If the Space Walker II flies anywhere close to the S-W in the simulator, don't try it as a second plane. It has a very "hard" rudder that could get you into a lot of trouble. A friend of mine has a Space Walker and he says that the simulator is accurate, and even thought he has been flying for 35 years, he seldom uses the rudder. Don't know if this will help you.
Glen