Could make GGenerals treat foreign-owned land as if it were neutral land when placing citadels.
You can already plant citadels in neutral land adjacent to your owned land, but if your land is pushed up against a foreign border you have to plant the citadel inside your own land.
If your GGenerals could ignore this and plant citadels in foreign land as if it were neutral then you could still get the 2 tile projection and leapfrog effect that Lebensraum gives, but without the massive 2 tile radius that eats tiles in all directions, instead of just the direction you were headed.
Don't know if that would be hard to do, but it seems doable.