This image might help a bit- this is a Hybrid with the foam insert removed, you can see the spare tire depression and on the right side in the red oval, there are two supports for the cargo cover, the difference in height is 4.125". In the upper position, the cargo cover is at the same level as the rear bumper.
As you can see in an image earlier in this thread, with the cargo cover in the lower position, it rests right on the center wheel part of this temp. spare. So in the upper position, you could definitely have something closer to a full size spare. cheers, roger