Steve-
I was having a bit of insomnia last night, and found myself thinking about my campaign in the deep of the night. Whilst considering the current situation, and a story I was plotting out in my head, I got to thinking about your new orbital habitats and shipyards. Currently shipyards are stand-alone, self-contained modules orbiting the planet. They cannot be armored or defended, except by other units.
What I was thinking about was that the orbital habitat rules provide a framework for large orbital constructs, and the shipyard modules are merely another large orbital construct. Can they be combined? This would allow the player to create armored and defended shipyard modules, if they want, and you could also require that the shipyard module requires a certain amount of "Crew" or population to be functional, which would require an orbital habitat to be built to house the module. Perhaps it wouldn't be necessary to require the entire population requirement of the module, but a fraction might be necessary to make it work.
What this would mean is that the player would end up with very large constructs in orbit around their planets, particularly their home planet. I feel that this is realistic, and an exciting part of empire-building.
Of course, this has several potential drawbacks. If a shipyard is expanded by including another slipway, this would change the size of the orbital habitat housing the shipyard, and its manning requirements.
Is this feasible?
Kurt