Some ideas to perks to smugglers:
1) Master of disguise: you can use the flag of any nation, but lose the benefit of dont be attacked by ships of the same nation you sailing; 2 points
2) Black market operator: + 20% income when selling goods to ports of enemy nations and +10% income when selling to your nation ports; 2 points
3) Professional barter: -10% of goods prices in any ports; 1 point
4) Smuggler runner: + 1 knot in OW, +0,5 knots in battle ; 5 points
also can be considered:
5) Stealth ship: turn the smuggler ship in a fake NPC (with no player name tag at all) turning the vessel exactly as you see one NPC trader in OW (8 points).