I just dismounted both the speaker (on the one side of the phone) and the display (on the other side of the phone) and can only confirm that the card tray goes inside in the midframe without even being visible from either “naked” side. There seems little point in me making photos as all what is visible is already in the photos that Meaghan linked to:
The card tray is BELOW what is visible in the red circle in the first photo here and BELOW the near-squared grey area in the lower left corner (to the left of the black and white warning sign) in the second photo here:
I also tried to measure how deep the pin goes to eject the card tray and this should be around 8-9 millimetres.