Too much of those PoB siegers flooding the thread.
I would raise important said points.
AFK siegers make harm time harm more than 5k haulers waste time to bring repairs.
Replace PoB upgrades and repairs to consuming very light weight (1000 cards take one unit of cargo space) commodity 'credit cards' to solve all problems.
PoBs already have veeeeery long time consuming of commodities. (10 units per second currently)
You could regulate that PoB would have automatic long enough time for repairs and self-upgrades to consume credit cards.