Ultimately, I think the question isn't really "how far is too far", so much as "how will this benefit the game's plot and get others excited and involved," as well as how charismatic and well-suited to leadership a character is. Since megacorporations are not a part of STE at this time, they won't just spring out of the woodwork, and interested players will essentially need to prove that they have the energy and ability to use a megacorporation to make the game more fun for everyone. Given that by their very nature there can't be megacorporations everywhere, we'd need to be pretty selective about who gets to run one. For existing characters who have been a part of STE for a long time, this will likely be based on their existing influence and track record (how many friends do they have? Are their friends powerful? Wealthy? Limited only to NPCs? Is there anyone who would be willing to form a partnership with them? Are there any characters who are fiercely loyal or devoted to them? What about their enemies? Criminal record?), and for new characters it would be a little more lenient since they have not had months to build that rapport.