Hmm. After exploring the front end of my car again, I've discovered 3 useful screws/bolts down below the bottom air intake, and the two (or 4) bolts that hold the horns behind the grill.

On my car, the center screw below is missing, along with one of the side screws. So I suppose I need to take off the bottom air shield to see what's going on there and figure out whether any of them can be used.

It puzzles me though that I've only found one other person talking about using the horn bolts to secure a license plate bracket through the grill. Maybe that's not optimal if you're trying to preserve the looks of your car, but here in VA we're accustomed to bulky license plates messing up the lines of our cars. But those horn bolts look like they could easily hold a bracket that suspended the plate in front of the thickest part of the bumper. At any rate, I think that's what I'm going to explore doing: fabricating a bracket that attaches to the horn bolts and pokes out between the grill pieces. Perhaps I'll secure the back of the plate to the bumper with a little 3M tape too for extra stability.

Thomas