Interesting discussion on enlisted/officer flight roles. The U.S. Army also employs Warrant Officers for rotary aviation, though regular officers can fill that role as well, I believe. The USAF certainly employs enlisted personnel onboard aircraft, though that's not as common as it used to be. Gunners would be a good example of an Airman aboard an aircraft... the only fixed-wing type in the U.S. that this applies to is the AC-130 Spectre as far as I can remember.
As far as FS bombers go, I'd never believe a story that the second crewmember was enlisted. By all accounts, that individual would be the WSO, which is irrefutably an officer position. You might argue that if support ships are multi-crew (I'd assume they would be), the "loadmaster" or the likes could possibly be a Warrant Officer/Flight Sergeant... you might even argue that the pilot might be as such, too.