[lunarhighway]

ground clearance is going to be an issue, as much as i like what you are doing here, i think unless they're designed to take quite beating you'll soon damage them.

the closer you go to the wheels the lower you can go however ... so perhaps it's a combination of a modest airdam (1/3 or 1/2 ) of what you're going now, and tire dams about the size of your dams now, plus perhaps an intertray could get you the same effect. a quick check on some randome profiles show the average passenger car has an angle from the airdams edge to the base of the tires of about 30 degrees, so perhaps that helps to check of what you make is in the save zone.

you can always go lower, but keep in mind sooner or later these dams might hit something