1. Have her rent the plane from the FBO.
2. Have her hire you for pilot services.
She has operational control, you are her employee as a professional pilot. Just tell the FBO the deal, some have a problem with it being 134 1/2 , others understand the distinction. It isn't 135 because the FBO isn't providing the pilot, only renting the plane for her operational control. She doesn't have to hire you, she can pick any pilot meeting the FBO's criteria.
To me, the 135 test is : Did the plane and pilot come from the same place, and who has operational control over it?