I pick the UN-aer thread because this goes counter to prevailing wisdom: Hug the ground and add wings for downforce. But I'm reminded of Luigi Colani's 'water strider' body that he raced at Bonneville.
justacarguy.blogspot.com/.../the-sebring-plus-only-car-i-can-think.html
The high stagnation point will cause a lot of air underneath the body, but a properly designed difusser would accelerate the flow and create an inverted wing situation.