So is the CoG of all planes modelled at max takeoff weight or some value less? If I understand correctly all planes are modelled with their fuel tanks right above the CoG so as they empty they have zero effect on the CoG thus stability due to CoG position does not change in game.
Ramstein makes a valid point if the CoG is modelled at some position that represents a full fuel load on the P-51. Althought I do not think he is grasping the concept that multiple tanks are not modelled in game and his request cannot be implemented as he would like.
The only thing that could possibly be done is change the position of the CoG to a spot that represents the rear tank being empty all the time and just give the plane less fuel (ie range) at 100%.
Disclaimer:
Red & Blue flame away. Personally the P-51 is fine for me, kills things well and also makes a nice target. From most FM comments I swear this game must run differently on each PC.