This 20th century aircraft model of missiles really doesn’t fit in well with the ships in ED which are on the whole enormous in comparison.....
Missiles are fundamentally an independent weapons system. They could be floating in empty space, activate, and function perfectly effectively. So while they might add some weight, they wouldn't take any power or distro drain, and because they're entirely independent of the ship, the models can literally just be attached to any point on the outside of the ship, requiring minimal or no modification to the existing ship models. This is especially true because drag isn't a factor, like it is with aircraft in the modern day.
Gaffer taping the missile permanently to the outside of the hull in areas that aren’t affected by any existing features such as heat vents and hard points is going to limit reloads just like existing torpedoes.