There is already a plan for a tanker version of the BFS, since as you note it wouldn’t be efficient to refuel with another crewed craft. I don’t see what the station helps with, though. That’s just extra mass to launch.
Managing logistics?
A series of BFR launches to station some fuel in orbit seems like a better choice than having to launch a fuel tanker BFR each time.
Why? I don’t see the advantage. It would make sense if one BFR tanker could launch enough fuel for multiple missions, which you’d then want to store somewhere, but that’s not the case.