Was interseted in your post. From whatt I know of RC Combat, there are some specific rules and criteria. Especially in the construction of the boat. In particular, a certain portion of the hull below and above the water line can only be a definite thickness and must past a specified drop test for penetration. That would rule out any diving designs you would have. Also, I don't know that you would be allowed diving as one of your defensive points. I believe Tuabman Plans had a set of prints for a 1:144 scale combat version of the Surcouf. I believe that sub would have been allowed two or three combat points: one for offense (one of it's guns) and two for defense (water pumps for damage control).
While the Argonaut might not pass as a combat boat, it sure would make a fine looking working sub.