I think there should be voyages for pirate legends that have a singular target that are challenging but can be done in a short period of time frame like the regular trading company's and you can pick which type depending on what you like to do, so to give some examples....
For those who like the gold hoarder voyage type once you find this chest you have to open it with the special combination by listening to the locks, when you think you have it you can open it, but if its wrong it explodes like a keg.
For those who like Order of souls type, your mind can connect to a special skull and your character can "walk inside the memory" different objectives when inside etc....
For Merchant alliance your boat is filled with gold crates goes much slower because of the added weight, you take on more water when you have damage, your ship also has a beacon everyone can see.
So these are all Pirate legend voyages, but they are much like the ordinary ones, you can choose which one you want to do, but more challenging.
