Dave, I attached angle brackets to the bottom of the bumper with self-tapping screws then bolted the lawn edging to the angle brackets with washer and lock nuts. So far it has been working wonderfully. I attached the coroplast side skirts the same way.
For those who may be interested, this is how I made my coroplast side skirts. I didn't have a piece long enough, so I joined pieces together with this method. They have held up very well so far.
