I assume the radiators will be in the shadow behind the solar panels and never facing the sun. That's seems like the easiest quick win.

Is the equilibrium temperature in orbit not somewhere between freezing and room temperature? If so spreading the heat evenly across the solar panels must necessarily be sufficient. Issues only arise if you try to get away with a smaller radiator or expose the radiator to direct sunlight or commit some other own goal.

The radiators then need to be protected from earth's heat/light if you want to reach 0K. I agree with GP, it doesn't seem great.