That would work most of time, but not exactly a great idea to mail yourself half a kilo of coke, and your both the shipper and receiver... That sounds borderline stupid to think this technique would go undetected 1,000 out of a 1,000 times.
I expect to meet with my daughter tomorrow, she's very involved with FedEx ground, at contractor level, not corporate level. She will tell me what measures are taken to the thwart this, but I guarantee you this much, you haven't stumbled upon some genius concept, nobody else ever thought of !