We need to keep in mind that there exist a variety of certification and operational requirements.
In respect of CG, you would need to do some research to establish what is critical for which consideration on which aircraft.
For instance
(a) stall speed usually is predicated on max forward CG and may dictate the shape of the forward limit in the higher weight regions.
(b) min trim drag generally occurs for aft CG so that is the region desired for cruise. I vaguely recall that even the DC3 OEM paperwork gave some guidance along these lines .. too far in the past now for the memory to home in accurately.