You can use rubber spacers or washers. Also you can bend the hangers and line it up better so its centered. You always could jsut leave it... it wont melt the bumper or anything but will make sounds of it hitting the bumper on bad roads.
Don't leave it!! I don't know about the exhaust you have, but I didn't think my bumper would melt either until I saw blue shit dripping down the side of my exhaust tip. It's an easy fix, and you'll be glad you did it.