I would follow what the pink man said , having played Seamus an awful lot, he doesnt really miss the convict gunslinger. I would change to either Sybelle or an Onryo and consider the grave spirit instead of copycat killer (i know its hard since hes such a cool little model!)
The grave spirit gives great tanking ability for either the hanged or sybelle and the Onryo can help get around the WP centric or Immune to Influence minions with one of her spells, plus combos with a hanged well too.
Keep having fun and keep us posted