NQ could implement virtual garage for all constructs static/dynamic to ease the server load. When you stop subbing your constructs would go to storage after two weeks.
When this happens player would be penalized and would need to pay 100k-500k per construct to retrieve em. When you pay the fee you will retrieve BP of the construct just like those XS vehicles with existing components etc..
This way we can achieve the same as implementing core slots but with less aggressive means.
Even though this will only solve the issue of non absent players. The infinite core issue could be solved with mining lasers on ships so people wouldn't need to deploy hundreds of cores to hundreds of territories just to mine lol.