Take the SZW and subtract half the approximate fuel for the zone. It's going to be in the ballpark of 5000 kg for the leg, isn't it? even if you use the lowest fuel flow possible (light weight, but with headwind you're looking at 4880 kg, so half that is still enough to take you just below 70,000 EMZW).
Having said that, I didn't use AFT, and Secombe made me do everything accurately (and it was easy enough to get through the exam in the time provided with very high marks).