Have you thought about other options for the bumper?
I am thinking that you can inject epoxy into the cracks in the bumper with clear epoxy, then sand it down to be smooth and just spray a few layers of primer on it. It doesn't have to be perfect, just smooth. Learn how to fix the scrape on the door with videos on youtube.com using touch-up paint and a few sheets of fine sandpaper. Then you could have the doors and bumper wrapped, too. If the wraps are done well, they will last several years. You could get an estimate for the wrap before doing anything else, if you don't want to do that yourself.