Before Photoshop had PAR options you would create graphics at 864x480(wide), than scale down in the project (using Distort/Transform, not Motion scaling). So, it's a solid process. :)
If you are using PS for graphics, I think since CS, you can choose 1.2 PAR in your new document settings - this would eliminate your 'not wide enough' issue.
Also, in Premiere, once your graphic is in the Project window you can right-click on the file and Interpret Footage... as 1.2 PAR. This will snap your Square 720x480 to Wide 720x480.