Just send it with proof of receipt (signature) required. That will at least prove that the package arrived at her house.If she s got 100 percent positive feedback, then the chances are she won t try to cheat you.
send it delivery confirmation, no need for signature, just the .70 cent usps way is fine. make sure to quick ship if she needs it in her possession in 7 days or is it notify her in 7 days. Take a picture send it to her that way she knows not to mess with u, a pic is very worth your time.