I have been watching this thread with interest.
This is exactly, what I was partly doing on the early releases of my Tool. I was scouring the game's datafiles for the different data, like sector lengths, pit entry points etc and the image files for trackmaps. I never found out or managed to crack the resources, where the trackmap lines come. I.e. this is the map which isshown on the screen, if you enable the live trackmap. If you manage to find out that data, then doing the trackmaps from the game real data would be doable quite easily. I haven't really looked at the game's resource files to find out the traces lately and most likely this data is in the game.dat file, so out of reach.
Due to the these challenges, I decided to do the trackmaps for each track by driving along the track borders. The good thing is that with these files, I can also know accurately sector borders, exact track lengths, show e.g. different flags for the minisectors, if needed, show DRS regions and I can "easily" do these for all games I support (AC, ACC, AMS2, PC2, KartKraft, rF2, R3E, DiRT Rally 2, Grid 2, F1 2012 - F1 23) and then the data is uniform for my uses. The data for my trackmaps used to be open, but I moved to a locked format when people were using my trackmaps without attributing them to me. As it takes some 30 minutes per track to do proper trackmap (outside/inside, racingline, centerline, pitlane and track area boundaries), I was not very happy on this "effort stealing".
So if you have 4 guys, you could easily create the trackmaps for the tracks and for your own tools use. Doing simple track borders would take 10 minutes per track (outlap, one lap on the outside border, one extra lap, one lap on the inside border), so with all work, maybe about 4 hours total. Might be much easier than try to map each track's distance with pixels and stuff̣. And most likely the trackmap images in the files are not exactly accurate. And the tracks are not "aligned". for none of the tracks the centerpoint of the map is not origo (0,0), but it always somewhere else, which adds extra challenge.
Cheers.