Each AI HW now gets a 'Guard Ring' just outside the core force field over the AI Home Command station (so the Guard Ring is not protected by the forcefield).
The new Guard Post Modules now slot into the Guard Ring as appropriate, with the Guard Ring have more module slots as the difficulty goes up.
Suddenly, I'm reminded of the battle against the Sa-Matra in Star Control 2.
I don't dislike your idea as one possible AI HW setup. But, if you remember, one of the poll items for new Core Guardposts was the
Tesseract Force Field - a puzzle item for defending the AI HW. It did pretty poorly in the polls. So did the
Flux/Microcosm Shield GP, which was another tactical variety-type guardpost.
I think it's unfortunate, but most people don't seem to want a whole lot of variety on the Homeworlds.
So, what would be good value for the "HW reserved" strategic reserves. 40%?
Actually, what is the current system for how the AI is willing to use strategic reserve on non homeworlds?
The current system is that the AI will deploy 5% (10%?) to the SuperTerminal system, 30% to any core world, and that's it.
A Reservist AI will additionally deploy 10% to any system with a "defendable": a Fab, Factory, or ASC.
I don't really think there should BE a reserved amount for the Homeworld. I think that if you can use other systems to completely destroy the Strategic Reserve, that's awesome! However, there should be a priority - if the HW wants ships, it gets first pick. Any leftover can go to other systems. Since the Reserve is contantly regenerating, this would mean that at least SOME Reserve ships would show up to help defend the AI HW.
Maybe also add a recall feature - if the Reserve is deployed (but still alive) elsewhere when the HW comes under attack, it'll be recalled and redeployed to the HW. That way you need to at least KILL the reserve to be rid of it.