I would say that we start with what we do know --- right from the beginning, WOB was evacuating people. It mentions 200,000 citizens on one world being taken... and how many millions were "missing" at the end of the Jihad.
Two, despite the Comstar Propaganda, which in many ways was the reason for the Jihad.... they claimed WOB had nuked Tharkad, before anyone really knew what had happened, and a LOT of the Jihad information was relayed by them..... and we know they were strongly motivated to present the WOB in the worst possible light -- the WOB was taking away some of their profit margin.
Three, after the war, a LOT of WOB people were taken in by Comstar, and it is later mentioned, they were helped to escape.... and the question is, escape to where?
Four, the Kheper and Ureaus -- at least some of WOB's engineers were helping the new Comguards --- even the names fit, as both are religious terms.
Five, the Thunderfox is mentioned as having some engineers from the Blue Flame .... we know some existed that way.
So, we KNOW they took more civilians and people with skillsets outside of the military, than Kerensky took with him, which means that they could, easily, colonize worlds.
We know they had access to all of the Explorer Corp records, and that they destroyed a LOT of information on their way out.... so we really can't say they wouldn't have had worlds to go to. Except, that we also know that they still had 3 that they had been building up on, for a while, and by the time one of those 3 had been found, it was dead, supposedly due to an "accident".... which could have been staged to keep people from poking around too much and figuring out WHERE they went.
And there are still 2 worlds that haven't been found.
I'm pretty sure that they are still out there - how many spies would they have still in the Inner Spere ... probably a LOT, as a LOT of ROM was unaccounted for at the end of the war. How many doctors or other surviving communities have their secrets in the basement?
And now, they could easily step out, and NO one would know .... just don't use their mechs in the stockpiles, or at least, none of the specific ones, like the Celestials, or Legacy. However, we did have a LOT of small factions running around stealing up military hardware.... and now, we have mercenary units appearing on the market, again.
Quietly fielding units, or even staging battles where units you control are on both sides would start generating a bit of cash... as would operating as tramp freighters ---- a LOT of those still exist all over, and are even more important now, as message carriers, than ever before. The Sea Foxes are not big enough to control all trade in the Inner Spere ... there are definitely other options for shipping, and other faction controlled jumpships .... probably still roving, and no one is really paying a lot of attention, right now.
Finally, no one is in a position to actually go after them..... let's face it, Stone did almost succeed in his plan.... he did sucker in Clan Wolf, and it was only the fact that Alaric invited the Falcons that they managed to beat the Republic -- it took both clans and the Falcons insane brutality. And for those that read the novel, you will know that Stone, in the end, grabbed Alaric by the short hairs, and left him in a really bad position.
I suspect the Hell's Horses are going to be a much bigger threat than they have ever been.... with the Foxes, Ravens, and Bears taking up more power, as well, at least in the Inner Spere Clan circle ... although, there is a much more interesting question.. has their contact with the Inner Sphere corrupted their rigid clan thinking? Will they offer anything more than just token acknowledgement to Clan Wolf? If not, then Alaric has deep problems..... The Hell's Horses have already, pretty much, stated they don't recognize the Wolves as the Ilclan. If the other three do little more than provide lip service... Alaric is alone in a hostile universe. Even if they do deign to acknowledge or help Alaric, will it be enough? Or, will they continue playing their own games?
So, back to the WOB / Comstar -- who, right now is even going to notice a few more mercenary units working and gathering money. Ones that seem able to keep their designs up on repairs, etc. As long as they limit themselves to fairly easily acquired designs, they can probably operate easily in the shadows, without much, if any, scrutiny. And with the amount of clan tech that showed up randomly in the various factions and groups... it won't be hard for them to build up strong forces.
They could already be operating quite freely in the open, as everyone KNOWS that they are dead and gone.. just don't paint your mechs in parade colors..... Comstar and WOB note that they use appropriate camo....
Nahuris