Or you can pick up Sorcerous Music (from Performance Magic, TMRE) which also specifically say that "the spell carries as far as the music [...] for some instruments, this may be a long way."
Mind you, instead of picking Sorcerous Music or the Deft Art or Quiet Magic that you need to pull this off, you can just learn the spells with Sight Range to begin with, maybe backing that off with one of the many virtues that help in learning or casting spells... and as a bonus, you don't wake up the whole countryside when casting a long distance spell 