I always laugh when performers don't fully know / appreciate all of the complexities of the backstage crew, though us bustling around doing a thousand things does sum it up pretty well.
Pendragon can tell you much more about his role than I can. My roommate did costuming, primarily for Fantasmic, and he did many many things. Things ranging from: laundering costumes, assembling costumes, transporting them, dressing performers, helping them undress (from costume), etc. And because this was a show where the performers did more than one role, he was kept very very busy with numerous quick-changes.
Because he was backstage 97% of the time he had very little Guest interaction, so he got to focus much more on the challenges of the show rather than the challenges of the Guests.