We seemed to be able to do it in AW.. The pilot also had to option as did crew to jump to different positions. But I remember flying as a crew member on many a large scale bombing mission with 9 other guys in the same plane.
I was also told by guys flying AW that it was also difficult there to get that many gunners for the 'average' players. Of course, I can't really comment on that for lack of personal experience.
But I do know that the standard player without years of play to make friends will never get enough gunners to make it worthwile. Even getting just one gunner can be a problem at times, especially if you expect him to have some minimum degree of skill level.
New players could totally forget getting their bomber's crewed adequately.
I think the AH solution (slaved guns, formation) is quite a good one for balance.