Doors and Airstair?

I am a firm believer in the adage; "If it ain't broke, don't try to fix it!". However, my curiosity has been aroused.I have noticed that the Sudan Airways (model PGK) aircraft is the only one that lowers the airstair and opens the Main exit when pressing the Shift + E buttons without using the 1 or 2 selections. This is a nice feature in that the Rear cargo door does not open, unless one presses Shift + E, then 2 or Shift E + 1, then 2. I realize that one wouldn't want the airstair to deploy if the aircraft is at a Gate. If there is a disire to have the Rear exit to open, an airstair should be available for that exit/entrance.Having stated thus; Here are questions for the aircraft designers:Is it possible to have an airstair for the Rear exit/entrance?Why is it that the above mentioned aircraft is the only Passenger aircraft in this collection which works this way?Is it possible to have an airstair for the Cargo models Main exit and a ramp for the cargo door?Thanks for any enlightenment,