I'm sure you could do it that way, but this applies a good amount of pressure on the lip, it does not move whatsoever. I'm not sure what the wind load is on it either, but after having a stillen splitter take off from my G37 bumper, I don't risk it.
This was using the supplied screws from stillen. Held on for a few months and one windy day on the interstate it took off.
As you can see the scews are still in place but they are small enough that it let the splitter pull over them. That's why I used the larger hardware to give it a good gripping area to keep that from happening.