I didn't really have an existing ship in mind - the concept I was thinking of was a ship with good jump drive, minimal manoeuvre drive, a cockpit and small crew area, but racks and racks of cargo containers. System ships would be in both the starting and destination systems to unload the containers and load others for the return trip, and the ship would simply do a shuttle run between two, or a few systems. As sideranautae said, it would probably only be worth doing in the core systems, along a regular trade route where a volume of trade was guaranteed.