Uufflakke, I'm worried that the inclusion of shipwreck in textures that are used by many maps would basically transplant the same ship on every map that uses the texture.
Also, I'm a bit worried about scale of the ship as it appears in the game - if you put a cargo ship floating on top of it, would it appear the same size, smaller, or larger? How would the depth of the water affect it?
It might be more interesting to look into possibility of making submerged ship models. I don't know if such a thing is even possible, or if all ship models are bound to the surface of the water, but it comes to mind that if you offset the geometry of a ship, and then place it on the surface, it should appear below the surface... but then I don't know if the game would even render it at all. I know ship models have parts under the water, but I don't ever remember seeing them through the water's surface.
It might be interesting to check this out anyway, because it certainly would add a new element to the game, to have ships sinking close to shore become shipwrecks for the duration of the mission at least... or for manual placement, of course.