Now wait a minute -- there is a BIG difference between "tested" and "deployed".
While the American G-suit was in testing as early as 1942, it was not in use until 1945. The first US G suit I can find being deployed was the G-2, available for issue in June 1944. It was large, heavy, and not issued without specific request. The first suit that was available as standard equipment was the G-3, whose design wasnt even standardized until March 1945. That meant it wasnt in common use until later in the year, by which time the sky was relaticely cleansed of LW aircraft. So from a military standpoint, the G suit had no appreciable effect on actual combat results.
You might consider it a "variant feature" of late P-51Ds, for example, but that doesnt mean that its effects should be modelled for OUR P-51D, any more than the effects of 150 octane gas or a 3 gun La-7 would be mandatory. (oops....)