Perhaps I'm being paranoid but I'm sensing a degree of scepticism here.
Mutt, we might be talking at cross purposes but, yes we do use specific take-off data ( paper or from datalink) for the aft CG case. Our ( Mine and Rainboe's) outfit uses the procedure on it's 747s at MEX, JNB and GRU and it adds a significant amount to the payload we can lift when compared with using "normal figures".
Capt Pit Bull: Agreed. This isn't just a paperwork exercise, the cargo actually has to be loaded properly to get the C of G where we are planning for it to be...otherwise the performance figures are not valid.