At one time or another, Dixie sold pocket models with 3, 4, 5.5, and 6 inch barrels made by Uberti or Palmetto. They list a 5.5 inch Palmetto on their web site now. CVA also sold them with 3, 4, and 5 inch barrels (these were made by ASM IINM). These longer barreled pocket models show up on GB, GunsAmerica and Auction Arms from time to time.
Good Luck in your search.
BTW, Palmetto doesn't have a great reputation; but, I've had a couple that were as good as anything else made at the time.