I'd rather see musketeer be the "job" and have ranger be the "class," or not even have a ranger involved in the process at all; I don't see them providing anything unique to the game. Corsair, or preferably a Gambler would be an appropriate complement to the musketeer, based on the game's lore, I think.

If there must be a ranger, it should come off of archer, or it can be paired with an additionally blasé, but highly requested companion, the thief.