There are often articles in Model Boats under 'Plastic magic' where the author has converted his model to run with micro equipment.
Action do a number of small components and try Servo shop for a micro servo for steering. Likewise see if they do miniature motors. One chap motorised all the shafts on his battleship.
The watchword is 'light'.
Good luck though, it is a relatively cost effective way of building up a fleet of capital ships.
