*nods* it's about an inch lower than it will be when it's done, I wanted to fit it to the bumper before bending the bottom edge under as the support/attachment for the undertray. And, I'm doing my best to have it be even with the underside of the car:
It's hard to tell, but I'm thinking about 2.5 inches is about how far down from the bumper the lowest parts of the car are. Also, the fact that this is almost a grass driveway doesn't help give accurate ground clearance pictures.
Right after I post this I'm going to put the other side of the dam on, then I'll take both sides off, bend the edge under, put them back on (snipping the ledge when needed for the curve), then I'll start delineating the cut marks on the undertray sheet metal.
And I test-drove this yesterday, just to make sure; even with the center unsupported like that, this still didn't bend (to the point of holding the deformation, anyway) at speeds over 70 mph. With the undertray behind it and extra screws, I'm thinking (that is, hoping) it'll be fine.