Here is an idea for a different Smuggler Voyage - it functions similar to a Gold Hoarder's Vault mechanically.

You start the voyage by getting a checklist from a smuggler representative, which instructs you to strategically place small calling cards, lighting lanterns and chalk graffiti on islands and outposts.
These items can also appear separately outside the voyage for emergent smuggler voyages.
Along the way, one of the spots you visit already has something present which you can note/pick up - this is the map fragment with the X marked on it.
Once you have completed the checklist you can hand it in completed to the nearest representative as well as the mysterious calling card you found for extra gold.

Or...you can go and investigate what the calling card was referring to.

This brings us to the 'Vault', here the calling card has map co-ordinates, which leads you to an Abandoned Shadow Ship.
An Abandoned Shadow Ship operates similar to how the Shadow Meg was going to work where it was only visible when you had shot up a flare.
If it's nighttime, the flare makes the ship solid allowing you to board and take the shadow variant loot items, but you only have until the first flare runs out - as similar to a vault it is meant to be time critical. However, having puzzle locks which secure the loot aboard the ship may be better, as it could allow co-ordination between crew members where one has to fire the flares into the sky, while the others have to grab the loot.

It it's daytime, the area around the Abandoned Shadow Ship is extremely foggy and dark so you still have to send up a flare to get this started.

The flares also notify other nearby ships too, enabling other player encounters too. Maybe good for an event to start with?

What do you think of this idea?