A6M5 as a stand in as an A6M3 and Spit V makes a lot more sense.
As for servicability, thats never modelled in the CT or any other place in AH. All a/c (even Japanese) had problems with the Pacific climate, as they did with the desert. The Ki-61 had bad serviceability in the Solomons and New Guinea as well. IJ metal could rust too, shocking as that sounds.
"The aircraft included in this setup are as close as you can get to the actual aircraft using the AH stable."
Not sure I get this at all really. The RAAF operated the Spit V there and its being left out, along with the P-40E, also absent, in their place, are 2 a/c that were not there, the P-40B and the Spitfire I. All that just for want of an A6M3? who's going to complain if the A6M5 stands in? at least its a workable setup then. No Betty?
The Seafire actually makes a better "Darwin Spit", because of the markings I think.
...oh btw, there were no P-38s, Hurricanes, or Ki-45s deployed in that campaign.