A big cruise ship can work pretty well for four or five vampires. (that's why it's a bottle chronicle) since there's always people coming on and off the ship and getting sick. To make things better, people often spend large portions of cruises drunk, making them easy prey. If a vampire can hollow out a few spaces on the ship, it's a pretty good environment.
One motivation I would have to use clanless rules in a bottle chronicle is so that unique disciplines like Thebian Sorcery have a chance to be featured without the need for an accompanying covenant.
As for piracy, I figure even a group of unaligned vampires could make a pretty good nomadic party on the high seas. They could always sometimes portray themselves as a "pleasure boat" of marooned partiers, using majesty to get aboard and take some blood (and possibly supplies and fuel) Daeva style.
Another possible chronicle is to have a group of unaligned vampires who own a plane and provide rapid transport whenever it's needed.