1) Rock Band doesn't have audience included2) Low Poly Characters of various descriptions have been produced by Marketplace Content Developers since Warlord produced his Low Poly Peeps Props. The Characters can be animated in the same way as eg; Chuck & Gwynne.
3) iClone has limitations as to how many Characters/Peeps you can have in a Scene without iClone Program Hanging &/or preventing you from Opening a Project..
4) Use Peeps for general people background use. Low Poly Characters for close-ups.
5) To get round the above limitations, you could have just Rock Band, Peeps & Low Poly Characters in their own different Scenes (Projects), using those Scenes as Camera Switches in your NLE Program.