Come to think of it, I haven't seen any back panels .fpd files floating around. The reason being that most chassis only have aluminum fronts. The rear is steel, so Front Panel Express won't touch it. I just drill the back myself and sometimes label it.
But for the Neutrik D Series, a 7/8" or 15/16" hole is what you need. And you'll have get the IEC inlet cutout size from the datasheet for your particular IEC.
Become one with the datasheet... I have a folder with a stack of datasheets for IECs, switches, connectors, you name it ! :thumb: