Try backing the car onto the ramps, so that the rear wheels are on the ramps.
Now you have access to the differential, and the entire rear of the car.
And, if you need the car level, you can then lift up the front end, and either place it on jack stands, or if you can the car high enough, you car rest the wheels onto a second set of ramps. This is what I do when I'm working on my Cayman, or my wife's Abarth.
