[mikeash]

You could, but I’d hesitate to call the result an SSTO, and you’d be better off using the whole BFR stack anyway.

Orbital refueling is critical for the Mars plans. BFR can’t launch for Mars without it, so the capability will definitely be there.

[fooker]

Add a refueling station in orbit and this setup requires less BFR + BFS launches.

I am guessing a BFR + specialized fuel container payload will deliver far more fuel to orbit compared to BFR + BFS + fuel.

[mikeash]

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.

[fooker]

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.

[mikeash]

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.

[asdfgl]

Orbit isn't just one thing. The plane changes (some of the most expensive types of burns) involved to get to the same orbit as a tanker and then to the target orbit would vastly outway any potential benefits.