This code works on one 5d3
menu.set("Cropmarks", "Bitmap", "CRSSMTR2.BMP")
menu.set("Cropmarks", "Show in photo mode", "OFF")
menu.set("Cropmarks", "Show in PLAY mode", "ON")
menu.set("Overlay", "Cropmarks", "CRSSMTR2.BMP")
but does not work on another 5D3. SD cards are different.
I'll try to test more later