Yeah Dick, the simulator is that good! But seriously, it gets you in the ballpark and gives a good impression and feeling of a model before building the real thing. Sort of proof-of-concept. Because it's not quite accurate in the first place it would be of no use in your case. Finding control throws by test flying seems to be the best idea. Once you have the real model, though, you could calibrate a simulator model to be very accurate and "virtually" practise to cope with the nasty flight behavior. We once did that with a very stall-prone F5B hotliner, which was as hard to fly as a helicopter.

iron eagle, the DC-3 rudder is huge and quite effective, but the problem might be that it's not really hit by propwash, in contrast to the stab. It might help to pull full elevator and have a steerable tailwheel. (That's pure guessing, though.)

The heavy glow-powered (as well as electric) versions are rather different models. I tried a 14.5 lbs version with .40 4-strokes in the simulator. It looks exactly like in the video of Charly Binder's electric model. Flaps are really advisable to get the thing to the ground properly. Of course there's no three-point landing as well. Only a tad more control throws needed. By the way, the C/G position given in the other thread (135 mm / 5.3") is quite far forward (as usual) and would require more wing incidence (4 degrees) or give a rather fast cruise flight. It's a starting point but 155 mm / 6.1" or even 175 mm / 6.9" is better.

A heading-lock gyro would be not a bad idea in case of engine failure. The engines are not far outboards and there's no problem in cruise flight. But disaster is looming if you add power for whatever reason, to fly faster, to climb, or even to deploy flaps. You know who you are, but I'm swamped in this case (too slow reflexes). I'd recommend smaller engines like .20 2-strokes (even the old .19 would still suffice, really) to make things easier. They surely give enough power and a more scale-like flying in addition.

The low-wing-loading / low-power electric version discussed here is child's play even in case of engine failure. Little rudder needed, even with full flaps. Full flaps possible even with only one motor running. Fault-tolerant if you're mistaken which motor quit.