But the Clans were not the Star League so what would they be creating? Basically the Clan Worlds writ large.
Anyway I had my own idea for an AU that would basically have started just after Tukkayid. In it the Crusaders would have wiped out the Wardens in the Home Worlds and severely hitting them in the IS. So the Wolves, Nova Cats, and others would still wind up united with Great Houses but that would give the Crusaders an excuse to relaunch the invasion. That's when things would really change. Just as the first wave is about to launch a new force would arrive in the IS. This group would be the descendents of a long, long, long range colonization fleet sent out into the deep Periphery by the crazy Cameron First Lord (I forget his name). This was a small fleet (a couple of warships, mostly cargo haulers, and a group of recon ships like the Bugeye [I think that's it name]) but outfitted and manned to be completely self-reliant since it would be so far away from the IS. The fleet, put together without any fanfare, then left right before the crazy Cameron left the scene (I can't remember if he was removed, died, or committed suicide). The clean up following the crazy Cameron saw the colonization effort fall through the cracks and be forgotten about. These colonists would get to their destination, get settled, and then send a recon ship back to the IS to check in. When they get back to the IS they discover they have been forgotten about and that things are getting shaky in the Star League (I think that's what happened in the canon timeline. Forgive me it’s been years since I read anything BT.). They decide to keep themselves secret and independent. Instead of eating themselves like the Clans their society stays unified and true to the ideals of the Star League. Therefore they send their time developing their technology, but with little use for weapons that area languishes. They keep tabs on the IS, but with numbers too small to make a real difference for most of their history they stay away. Then the Clans arrive in the IS. This threat causes the colonist, now with a population large enough to be a real force, to go on a crash course of military development. With their super advanced technology they quickly develop mechs, aerospace fighters, battle armor, tanks, and dropships. Warships, however, take a little longer and they are still short of them when they arrive to stem the new Clan invasion. Having kept tabs on the IS they know who to deal with (yes to the FS and DC, no to Comstar, FWL, and CC). With this new source of advanced tech the colonists (who can claim legitimate decent from the Star League), FS, and DC start beating back the Clans and eventually start turning some of the less fanatical Crusader Clans to their side. Eventually the last Crusaders are chased all the way back to the Home Worlds, are destroyed, and with them the Clan culture. This has been an idea rattling around in my head for years with little (or no) research or outlining done on my part.
So other then that I don't have anything to say.