Alright, let's give an update.
I went all in on skipping the artifact in Laurion (for now, at least), and instead, based on my optimized santoblast loop 5-save went for Astrape instead. And man, are there many ways to play this! I do not know how far off a "perfect" run I am, but I suspect it it possible to clear Astrape (excluding the aircraft obv, but including all blue actions) by the end of loop 10. I did not manage that, but I did manage to find the faster path through the highlands, get the artifact, and even quite a few blue actions that are not requisites for getting resources or the artifact by the end of loop 10. Most admin and civilian blue actions are left though. I'm done there. The first loop I got to Astrape was loop 8 - loop 6 and 7 was pretty much the same as previously, just optimized for getting to Astrape instead of going back to Laurion. Key for 6 is to get to Laurion and get water and fuel, for 7 just fuel.
This took so many attempts and re-attempts and sheesh. Just getting the most out of everything but still getting away from Santorini in time in pretty much every loop, one way or another. Especially annoying when trying to get to Santorini and back with the tram in as early a loop as possible! I still have a bunch of blue actions in Santorini because doing them would delay solving Astrape! I suppose, though, that now that Astrape is stable I could park the rover in Santorini, take the tram and do all the blue actions in Astrape, get back, do all-or-most blue actions in Santorini, then start heading for.. I dunno.. Pneuma?
I'd be happy to get some input, what should I go for now? I'll probably take a break and start enjoying summer a bit more now though, lol