Generally the plate goes on the crown piece, kind of by your horse's ear. I've never seen it done but I suppose you could put it on the cheekpiece, if it was narrow enough (it might be too wide).
Yes, it was George Morris who hate nameplates. He is ultra conservative but his argument is that the focus and attention should be placed on the horse. Any type of bling is just a distraction from what should be the center of attention.