It’s a few hours till showtime at the Fillmore Miami Beach. Doors will open for Coheed and Cambria at 8 p.m., and around 4 p.m., the production team is inside readying the stage, running through a never-ending checklist of preshow preparations. Backstage, in the narrow hallway that cuts through the rear of the venue, a chubby yellow Lab named Bella, the unofficial Fillmore dog, trots past offices and dressing rooms. It’s quiet and decidedly not chaotic. This is hardly the first show to happen at the Fillmore, after all.