I think you're close, but the background color turns everything black. What I'm trying to do is create an 11x17 with a 1/2" black border around each side and the rest of the page white. I can't figure out how to add the border correctly.
If you are going to have a stroke around the whole image, then I would make the cell size about .05" larger on each side. If you have a trimmer that has measurements on it, then just selecting "crop marks" will give you exactly what you need.