POB Siege Balance

[LaWey]

EVE have example of working gameplay concept of destroyable base in openworld game.
As i wrote before it have next components:
1) Specialised siege weapon
2) Base have vulnerability time settings, so owner know when attack possible.
3) Siege happens in three short stages.

After some discussion with decktare, he pointed that vulnerability time chosen by owner will probably suck in discovery. I kinda agree, have no statistic on server, but certainly we havent so much people to cover any TZ on any faction. Any ideas how it can be adapted?
In discord was idea about cooldown between siege attempts (basically its that "dead for 3days bs" thing) not sure if it good.