Depending on what update you have (U5.0 & above), you can enter a CRZ CG on the PERF INIT page.
But I always understood that all this does is spit out a MAX ALT and OPT ALT that are correlated to the actual loading of the aircraft on the day.
Not saying anyone would, but you can artificially increase your max Mach at altitude by entering a more rearward CG location in this position.
But it is purely a software issue and has no correlation with stab position whatsoever. U10 and above will spit out a stab trim setting for a particular CG location but you still have to
manually set the trim. Its just a database lookup table behind it.
Assuming your loadsheet is reasonably accurate, the only way you can adjust the propensity of the aircraft to come unstuck at T/O is to set a trim setting slightly more nose-up than the computed one. The dangers of this are obvious.
For most efficient cruise, you do want a rearward CG location, so all the bags should be in the boot.
There is a trade-off in terms of controllability but there always is isn't there?
