If you plan on releasing the coon, then go ahead and get a hav-a-heart trap. If you plan to kill the coon anyway, don't bother with any of the box traps. They are often too picky to keep them running when you have an animal as strong as a coon in it. Get some of these:
Amazon.com : Duke 0510 Duke Coon Trap, Pack of 2 : Clothing
I set them out with some canned cat food in them with a marshmallow tucked into the top of it. It cannot catch a dog or a cat, but can catch a coon or possum. I attach it to a fire log with a stout deck screw (3.5"). If you have a family of coons, you will catch one a night until they are all gone. Ask me how I know that.

Then, when you catch one, your backstop is the ground.