I can't help thinking that DT is full of great cameo roles.
What about -
Kathy Bates as Rhea ( yeah, I know she's wrong physically, but she's a great actress and just think what she could bring to the role) or maybe Meryl Streep?
Billy Connelly as Tick Tock?
Steve Martin or Jim Carrey as Dandelo?
Johnny Depp as Eldred Jonas?
Ron Perlman or Bruce Willis as Cort?
Long days and pleasant nights