I can't wait until this is available. This means I can put Naval Battles in Barbarian Invasion! And finally expand IBUR to cover all of the Barbarian peoples of the 5th century!
Hannibalcaesar did it in my mod, but only for Alex.exe, and it was really hard, but possible. Basically it was a carriage ballista or war elephant with a different model, texture, stats, and animation. They would sink if they got exhausted too, and you had to edit the whole campaign map cause you couldn't carry units in ships anymore, but it worked.