So, something I think may be viable is maintaining good relations with other factions (well, "tolerance", which is as high as it seems to go). I started an Academy game, took USA, and have been playing a sort of laid-back research-focused run. I bribed everyone up to tolerance (a few boost early on is all it takes) and signed non-aggression pacts with everyone, and it's now 2032 and I don't think I've ever been targeted by a hostile mission. I don't even think they're running public relations campaigns in my territory (if they are, they're ninjas). None of my stations have been taken over either and my research income is triple the next faction so, things are going alright. This is in stark contrast to my previous Initiative run where I almost completely monopolized LEO, the moon, and Mars, and then constantly antagonized everyone by taking over what few habs and stations they managed to get up and running. The result was a nonstop flurry of attacks, assassinations, sabotaged space facilities, etc. It was awful.
You can even coup nations (I haven't tried straight-up purging yet) without breaking the non-aggression pact, though it does lower relations from "tolerance" down to "in conflict" (edit: actually, I'm not sure if it was a fluke or what, but the next time I coup'd someone it did break the pact, so maybe it's only fine if you're undetected?). It's possible that by maintaining good relations, the AI figures it has bigger fish to fry and prioritizes targeting their actual enemies. I mean, it sounds kind of obvious, so it's probably some kind of GSG/4X brainrot that made me take 40 hours of gameplay to realize cooperation/diplomacy might be a reasonable strategy.