I was just looking into this as well. I got rear-ended the other day (not super hard) and was under my car and noticed the bumper support was bent, but also quite rusted as well. I was planning on just removing the bumper cover. Did not look like a difficult job. Here is a video showing how to do it:
The rear bumper cover kind of wraps around the support on the bottom, so not sure you could get the bumper support off without moving the bumper cover. If you find out you can, let me know!