I don't believe any of the cruise lines are allowed to give out listings anymore due to the data protection laws etc. Some lines used to have the full listings on show, but that's going back about 20 years, but you might be lucky.
I guess if you wrote a covering letter to cruise H office enclosing letter (which they could reaad ) they MAY forward on to passenger but do not hold your breath data protection etc as above .
I doubt it. Data Protection, Human Rights, Civil Liberty's & any other loony committee would all need a months holiday to get over the shock!! Shipping Lines stopped issuing passenger list's many years ago. P&O used to put one in your cabin folder, but that was a long time ago!!
The days of passenger list are long past. In the 50s and early 60s there was always a full passenger list left in each cabin. Of course in those days they were liners normally taking expatriates back to their place of employment. In the current age of cruising people are much more secretive. Also, in my experience some are travelling with "friends" and would prefer not to let the world know about it!!