Well, while posting my last two stealth achievement threads, I noticed these screenshots from earlier this life in my folder. I figured that since I was in a posting mood, I'd throw these in for free.
This was a single kill run with only the required boss murdered. Everything else was stealthed. If memory serves, I was able to get all the crests and open the chest without aggro (lucky placement), but I believe there is no way to blow up the explosive barrels on heroic without drawing aggro. The lizardfolk always hear the barrel explode and come a-running, though you can duck downstairs quickly before they come for you. In the hold, on heroic, it's basically impossible to break the barrels without drawing aggro (either with melee or throwing). On Legendary, it may be possible using assassinate to break barrels without breaking stealth... or on other builds with attacks that don't break stealth, ie. stick build and sweeping strikes, though I will need to test that further. Likewise, there's no way to not aggro the Cabin Boy when attacking the Captain.
Still, I thought it was pretty smooth. So here it is for your enjoyment.