[Christ]

Blast it with a heat gun on high for a few minutes, that will help get the wrinkles out.

Sometimes you can find that stuff with a rounded edge and a bit of a flange on the other end... the flange makes it so you can mount it under the bumper instead of on the bumper, making it a cleaner install.

Since you've already mounted it through the front though, nothing much you can do to fix that. If you're worried about the screw heads showing, you can get plastic caps that the screws go through, then there's a snap cap that fits over the main body to cover the screw head. You can get them in several colors including black.