The ones who have had illegal genetic enhancements
would probably do what the Bashirs did and keep it a secret and try to live out their lives as best they can. We only know that Starfleet actively bans them, but the general stigma that seems to still hang around would keep most from wanting their secret to be known if they work or live with humans. They really shouldn't have to face this. For the few that are like Bashir should be able to pursue any career path they wish and to be treated with the same dignity as everyone else. This is meant to be our "enlightened" future after all.
The problem is that Bashir seems to be a rare case. DS9 gave the impression that the available methods and technology were more likely to create someone from the Jack Pack rather than a Bashir (I can't remember, but weren't the Jack Pack the least severe cases as well?). So I can understand why they would want to ban Humans getting unnecessary genetic enhancements if the chances are high that it is going to mess up the individual receiving the treatment rather than help them
As for working with the Ferengi or Romulans, they would have a worse time. Those outside the Federation don't seem too fond of ordinary humans, I'm sure they would like super-humans even less.