Thanks khaye1 for posting the idea about the autozone license plate holder.
I didn't really like the tow hook idea, so went with the autozone holder. But fastened the holder without removing the bumper or even the grill!
I got 2 11mm nuts and washers from Home depot and painted them black, along with the other parts from the holder. I glued the washer to the nut so that I could use the flex head wrench from Gear wrench set.
Put the nut with the glued washer into the flex head wrench, and bend it about 45 degrees and insert through the grill opening. Use the allen key and bend the flex head about 90 degrees, so the screw on the holder aligns with the nut.Fasten the holder to the grill.
I got two 5mm X 10 mm bolts, and extended neoprene nuts and washers. This holds the plate to the top part of the license frame, and also the neoprene nuts do not scratch the bumper.
Looks like a neat solution without drilling holes, or using the tow hook cover.