I just noticed that the DOS version counts days from day 0, while the GOG version counts them from day 1. So my previous post's "day 9" victory was equivalent to day 10.

Well, upon examination, my optimisation was a lot sloppier than I remembered, and it wasn't hard to tweak the last few days' decisions it to achieve a victory one day earlier. So this is a proper day 8 (DOS) victory, equivalent to a day 9 here:
https://drive.google.com/file/d/13WVllxoQR6DZFdquUrzOnzmKDgaHlL93/view?usp=sharing. (I wonder if I could have done even better by optimising properly from day 0?)

I'm gonna see if I can replicate this in the GOG version when I have the time.

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EDIT

Yep, I can not only replicate it in the GOG version, I can pull off a victory on day 8. (Would have been Day 7 in DOS). But at this point I'm hijacking the thread, so lemme start a new one.