Are they? If they would ever happen where would they fit better? Nutrek? DS 9? Current Lit universe? Sorry but i cannot check every book that is out there.
You might want to check out (I think Jerry Oltion wrote it) "Mudd In Your Eye", since I can't think of a better smuggler in Trek than Harcourt Fenton Mudd. J.A. Larence also wrote "Mudd's Angels" for the Ballantinie Trek line, which countians the live-action Musdd stories and a "new" story.
I can't remember, were the main characters in the Seven Deadly Sins: Borg story mercenaries or smugglers?
Vanguard has a smuggler as one of its main characters. Cervantes Quinn was his name.. http://memory-beta.wikia.com/wiki/Cervantes_Quinn His story may interest you...
^Beat me to it Paris. Quinn is the best Trek smuggler! He is one of the reasons the Vanguard books are so cool