I'm not sure if this is what you've already done, but you can get at some of the panel from the backside by removing the rear trim.
I've been involved in some parking accidents, about a year ago I was backing out of a parking space, and so was the woman in an escort backed into me, only scuffed my rear bumper, not a biggie.
The other time I had to back around my mom's minivan in the driveway, she parked right behind me (for no good reason) and I backed out too sharp and scraped my driver's door on her front bumper. Her van, nothing, but my door looked like ass, all crunched in. I told my mom I got hit in a mall parking lot, it didn't matter cause my insurance doesn't cover my car, but it worked anyhow. I paid for my own repair myself and then I told my mom about it once she sold the van. we both had a good laugh...