Well the first part with mentioned 30 tons. I looking at the largest ship that can fit in a Large ship which is a Sidewinder. Even if they took out the Frame Shift Drive of the Sidewinder and replaced it with 4 cargo It give the user at the most 16 slots. That 2x Size 1 Compartments
3x Size 2 Compartments.
It best for players to start using common sense when they accept missions. Have a Python if you are doing a Small station. Or you are going to be dealing with a lot of Docking and undocking both Ship as well as Station if this idea was ever added.
I misunderstood... again, (I do a lot of that)
If you were to have a Cargo Shuttle it would not have to have all of the modules in a sidewinder (and presumably not even resembling one either) it would just have to be a container with a cockpit at one end and an engine at the other, perhaps a bit like a container wagon, drop off a full one and pick up an empty one... or full of a different cargo, whatever, either way the player could entertain herself/himself ferrying cargo back and forth, this would add gameplay for those that chose to do it and would annoy the hell out of people that don't want it.