You've actually flown a P-38 in real life to know this? Just curious...
Unfortunately, no, I haven't managed to fly a P-38 in real life although I do have about 5,000 hours in a twin tail, twin engine airplane including some " unusual attitudes".
The rudder effectiveness in AH for many airplanes is seriously undermodeled in my opinion, not just the P-38.
However, my opinion is only based upon my 30 year career in aviation and very long time study of aerodynamics and aircraft performance and should be generally disregarded.
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Counter rotating props? Are you positing that they cancel each other out?