It's a bit of a waste of money, but Middle Atlantic AXS. You can get them 16" deep. You would throw away the rails and wire management, but the base is similar to a Slim-5 and you can bolt a 5W caster set to it. This is actually what i've done in my house. In my old house it was built-in to a nook and that's why i went with AXS. In my current house it just sits on the floor in a closet.