[Spraug]

You already mentioned that Surcouf sank near the Bermudas, but - had she survived - I think it is likely that a) she would have been refitted (Radar instead of the airplane and improvements for a dive time less than the 15 minutes she originally needed) like most other pre-war vessels and b) that she would have been used in the Pacific because there was no scope for a ship her type in the Atlantic or Mediterranean.

Also she was not meant to fire broadsides but to fire strait ahead (maybe 45° to port or starboard) not much more, so the recoil would not have capsized her.

I can only agree that it would be a cool boat to try out. Maybe only available after 1943 or only in a specific campaign, but it would be cool (Sorry for all the 100% historically accurate people, but I like alternative history approaches). Unfortunately I have no clue about modding, so I will have to wait if someone else takes pity.