You know how when you're in supercruise and targeting your destination station, the 3D model of it on your HUD lets you know its orientation relative to your position?
Well, what if making a docking request highlights the location of your assigned landing pad on the 3D model of the station?
Alternatively, the 3D model could be replaced with a map similar to what Misty_Dark or Para Handy posted above, with your pad highlighted clearly.
That way you know exactly where to go as soon as your docking request is approved, without having to wait until you're through the slot to follow a compass, and without having to memorise locations, and no changes need to be made to the stations.
The other advantage is that you will have a better idea of what speed you should be coming in at, relative to the distance of the pad from the mail slot.