Trading Subsidiaries as Ark-like ships

Instead of only building subsidiaries as improvements, there could be the option to create giant Ark-like ships, that:

• Can move slowly. The design lacks support modules.
• Cannot attack, only self defend. 
• Can be anchored on owned/allied/peace systems and asteroid belts (making them more relevant)
• Generate trade routes to the HQ once anchored. Only can be anchored if maximum subsidiaries allow them.
• Can be destroyed as arks, and like arks, can be recovered by own fleets
• Can be pillaged by enemies in a short lapse (2-3 turns) and give high amount of dust
• Trade research give more slots/health/speed to these mobile stations

The HQ still should be built on an owned system