[Jason Warth]

I’m not sure if you’ve been over-thinking this, or if the ability I’m about to describe was unavailable at the time of your post. In either case, there is a MUCH simpler solution than using a third-party macro.

When recording an Action in Illustrator (or when editing an Action), click on the fly-out menu in the upper-right corner of the Actions panel and select “Insert Menu Item.” This will open a dialog box in which you can type the name (or partial name) of a menu command and click “Find.” (Note: instead of typing the command, you can instead click through to the actual menu item you’re seeking—which is a bit counterintuitive, since normally, menus are disabled when a dialog box is open.)

In either case, the menu item you’re looking for is “Fit to Artwork Bounds,” which will resize the artboard to the exact height and width of the document’s artwork. (Note: “Fit to Selected Art” is a similar option, but differs in that it resizes the artboard according to the selected art, rather than all the art in the document, as the previous option does.)

Whatever method you choose (i.e. the “Find” button, or actually selecting the menu item), once the correct menu command appears in the dialog box, click on “OK.” Now, your action contains this command. Make sure to stop the recording of your action (unless you were editing a an already-recorded action, in which case, it should already be stopped).

Hope that helps!

-J

P.S. If you’re curious, these menu commands are found under the “Objects” > “Artboards” menu.