Payload COG Shift
When the Payload is using the Body Length (automatically fitting) then shifting the COG will keep the Payload in place. The COG can be shifted by dragging the COG through the gizmo, the dimension or the property panel.
If the Payload is not using the Body Length then the COG will stay at the centre of the Payload, and shifting the COG will move the Payload as a whole forward and backwards.