Ok, I muddled around with this idea for a couple days waiting for inspiration and I think I came up with a combination that I like.
The plan as it is now is to allow all the ship hulls to be built at level one of ship construction. Instead of adding a bunch of hulls though I am doing what was suggested and adding a component that modifies maintenance. I tested this and it does work fine. This will allow designs to be upgraded.
For those that are interesed in the details, I have changed the exsisting Life Support component to "Primary Life Support" and added a One per ship restriction to it. I then am adding a component with life support ability called "Engineering Deptartment" that is also one per ships and is larger and more expensive than the Primary Life Support. In the component description I state that this is required for ships and bases larger than 500Kt. Since the pimary life support can only be added once, people should use the enginering dept for cruisers and above for the second life support comp.
Then I am adding an "Auxillary Life Support" that is also larger and more expensive than the primary life support and Engineering section for the larger ships/bases that require more than two life supports.
At higher levels of ship construction the engineering dept and auxillary life support will be smaller and less expensive, but in the early levels they will be large enough and expensive enough to significantly restrict the effectiveness and efficency of larger ships. Also they will never be as small as Primary life support so they should never be used in place of Primary life support, although there is really no way to prevent that if someone wants to be contrary.
Also at higher levels of ship construction the Engineering Dept will offer progressively larger reductions in maint, which will make the bigger ships much more useable later in the game.
I am also considering furhter penalizing the larger ships early in the game by giving the hull a maint penalty which will be offset later in the game by the engineering dept.
Geoschmo