Get an x-pen, also called a puppy pen or an exercise pen. They're small pens made of heavy metal wire fencing. They give the pup an area not too much bigger than a large crate, and they sit right on the ground. Set up the x-pen in a grassy area with nothing else on the ground inside it, use a few tent stakes to stake it to the ground so it can't be knocked over if the pup jumps up against it, and put her inside. She doesn't come out to sniff, or play or go inside, until she goes potty. As soon as she goes potty, out she comes with much rejoicing, apply treats to puppy liberally, and then it's play/explore time, or whatever else she wants to do. Her reward for pottying is to get out of "potty prison". It worked pretty well for the little boy I fostered last summer--he had nothing in the pen to distract him from business at hand, and he *really* wanted out so he learned to get to work in a hurry.
