Depends on the dog and the tummy. My dogs are about the same size and eat 12 inch bullies without a problem. I've given a 6 lb dog a 12 inch bully, and she would eat about 4 inches at a time without a problem. my friend's 40 lb dog had an upset tummy with a 6 inch bully.
If you're prepared for possible tummy issues, and your dog has had bully sticks before, I'd probably let her go to town, and just pick it up if/when she walks away from it