[M_a_t_t]

If you raise the back, lower the front or both you create more down-force. The smaller gap from the lower front makes the air expand under the back and "sucks" down the back of the car. I think that alone would counteract any gains seen from making it adhere better to the template.

I think there is still merit to the thought though. If you made a belly pan parallel to the ground at the same height as the front bumper it would eliminate the vacuum effect at the back. It would then conform to the template better. But it might increase the Frontal area a little bit. Too many variables to say yes or no I would think.
I know there are others on here more knowledgeable than I that could verify or deny my initial thoughts.

Matt