I'm working on a small alteration to my VonDos' ships mod that will make his ships unique and will drastically reduce the chances of you coming across them anywhere except their historic routes.
At the moment, VonDos' ships are all ship type 103, the same as Chatham Type, Ocean Liner, Large Troop Ship etc. That means that there is a good chance of multiple unique ships turning up in one convoy like the one below that had three SS Normandie and an RMS Queen Elizabeth in it. Great for tonnage, not so good for historic accuracy!
I'm working on changing the ship type to 100, which only contains the CAM Freighter, Ammunition ship and a couple of other ships. Type 100 is hardly ever used randomly in convoys and, even where it is randomly used, you'll get
one unique ship rather than many of them.
It's exceptionally time consuming as every ship needs to be tested in its new configuration (and there are
nine full campaign files to adjust) but I'm hoping to release in the next week or so.