I would say start out with a heavier bite tippet, and if you get bit off once or twice then add some wire to be safe. I've lost a few flies to mackerel fishing around them. As for the sinking line, it would depend on how deep the water gets. I've done all my saltwater fishing in general with a floating line and managed to catch a few snapper. I'd be concerned about the sinking line getting wrapped up underwater on something with all the water moving in and out constantly. I don't have a whole lot of experience on jetties though, just a week or so the last couple years when I make it to Florida and there its just 2 short rock jetties that don't go out more than 50 yards or from shore.