Unless the passageway to these two dungeons is guaranteed open 50% of the time (ship captains do go to bed), I would strongly advise against using the mists for this. Perfidus has an extra reason to be difficult to reach given its high end resource farming and also status as actual hell on earth. Two random islands for the mid levels do not make nearly as strong of a case for being hit with the "you knew what you were signing up for, outcast" baton. Devs, please, we have literally had the opposite be done several times over to accommodate outcast access to dungeons and content, don't start walking the other way now. Who were the bypass routes made for in Berez (caliban under cell, alchemist laboratory), VoB (werefoxes, swamp hag, assorted gribblies), and Port (university to enchant, black watch)? To say nothing of lake Zarovich now being a complete loop giving extra options to bypass Vallaki. It's certainly not for the people who can just stroll through the gates, I know that much.
To add to this, historically the marchand and ouvrier are the places in Port other than the underground where caliban are tolerated. You need only walk across the street from the docks to find one gainfully employed, so changing the dockmaster to refuse them now would be a strange move without existing justification so far as I'm aware of the scene and setting.
