Differntiating Hull Sizes

[Suicide Junkie]

Sure. Just set up a racial tech requirement on the hull sizes instead of just "ship construction".

[Slick]

If you are interested in cramming more stuff in a given hull size, you can make a mount system that reduces the size of components. You can make mounts have tech requirements; i.e. you can control who gets access to the mounts by research/tech. Some mods do this already.

[kerensky]

The Proportions and Devnul mods do the afore mentioned items and would be a great reference for this.