is it simply just not possible

[GoldenRivet]

to mod playable surface ships into the game?

I think it would be a blast to start with a flotilla in like 1940 and try to break out into the atlantic by way of the denmark strait and engage merchant convoys while playing as a German Battleship or Battlecruiser.

no diving to evade aircraft or destroyer groups - all submarine tactics out the window - this would be a whole new ball game.