If your going to do it half ass I would leave it the way it is. Not trying to be rude, but the bumper covers are fairly inexpensive on craigslist, ebay, or even rockauto.com. I wouldn't suggest using a material such as the one you are asking about. They make the plastic welders for a reason. If your going to do it, do it right the first time. But if you think you have found a way to get it done, then do it your way. That's the joy of owning your own car, you can do it how you want.