"Why would doing this be fun?" If you can't answer this, then maybe the feature doesn't belong in your game?
has any escort mission ever been "fun"? <g>.
sometimes they are challenging. often they are frustrating or simply boring. it seems the reward is usually the prime motivating factor. whether it be treasure or simply being able to continue the quest line.
in this case its a one off, stand alone, "side quest". so the reward treasure is the motivation. i'm leaving it up to the normal operation of the game world simulation to make it challenging (random encounters and such). accelerated time should take care of the dull parts. which leaves avoiding frustrating behavior - such as slow suicidal NPCs you can't control.