G'day Von
I only found this out because I converted a campaign by nyalex09 to B.A.T. (will be released here).
He had a flight of P-39Q-1's strafing shipping, couldn't believe my eyes.
My findings are that the P-39D-1, P-39D-2 and P-400 ignore ships just like every other aircraft I've tried.
An even less elegant method to get AI to strafe Ships is to give a vehicle the ships waypoints, probably not so bad for night missions.
EDIT
Thanks Lars
If we could build a list of aircraft that would be great for us mission builders, especially in New Guinea and Solomon Islands.