Weighted PPG is an interesting idea which seems to make the most sense.

I was curious about how the Championship would look under this scenario, as I can't see them playing any more either.

Sheffield Wednesday would have 59.85 points.
The final relegation spot would be Charlton on 48.08 points.

That means a 12 point deduction is what would be required to take them to 47.85 points and into the relegation spots.