Perhaps you could do an investigation type run. Local city has fallen ill (have to discover contaminated water source). Part of the local plant life is dying. Town has been poisoned, monk has to go out and collect the ingredients for the cure.
Is it possible to 'train' a bag of devouring to be a sidekick, or a familiar. Does the bag have the intelligence to learn to trust you to feed it, and not see you as just the next tasty treat?