Big ship supremacy... Can little ships keep up?

[PvK]

See Heavy Torpedoes and Anti-Matter Torpedoes in Proportions 3.x. With some research they can be quite powerful, but the mount is based on _warhead_ technology rather than ship size, so larger ships tend to use longer-ranged weapons with size-based mounts, but a small inexpensive ship can mount these weapons. Very similar to what you were suggesting, and again, I think it works well.

PvK