So if I remember correctly (and it's been a long time), the first game had a system where you built wooden barricades on windows. I think these should come back especially for better defended outposts (so we don't have zeds hopping through and breaking every single window thus attracting more) with the addition of a system where you can upgrade defenses on whatever base you choose. Such as tiered perimeter wall upgrades.
Tier 1: Chain-link perimeter fence
Tier 2: Sheet metal perimeter wall
Tier 3: Brick laid perimeter wall
Tier 4: Cement perimeter wall (With construction worker skill and lots of materials)
Something of this nature. Just an idea :)