How do I export all artboards to a png without cropping?

Question

I've got a 2x8 (wide) grid of artboards, and would like to export all of them to a single PNG as they appear.  Unfortunately, Illustrator (CS6) is cropping the edges of the PNG to the objects in the artboards, rather than to the edges of the outer artboards.  Is there some way to change this behaviour?
I've tried creating an unstroke, unfilled object that encompasses all of the artboards, but Illustrator seems to be ignoring it in the export (presumably because it's not printed).
Are there any other tricks I can try?

Answer 1

Then all objects need to be on one artboard. If you want the layout like you are seeing all the pages from a distance. Then create a rectangle that fills each artboard and give it a stroke. Group the page, then move all the groups to a single artboard. Select all, cut, paste. The artboard that contains all the objects can be scaled to fit the contents if necessary. (found in the artboard properties) You may want to create a rectangle to the large artboard as well so the page size is correct when saving to png.
If you want to keep the artboards for other exporting jobs. Do the above on a copy of the ai file.
You know what, before doing the above, just create a rectangle on the large artboard so that it surrounds all the artboards. Export that to png. When writing the above, it dawned on me that it is necessary to create a page border so that the image crops correctly for the page. Jeesh, I wish I could think right... Anyway, one way or the other should do the trick.