The easiest way to get your weights is to run across the scales while out traveling. All Flying J and Pilots have scales (or most anyway). Simply go in and pay your $10.00 and get your scale sheet.
Then wait until you are unhooked (camped) in an area where there is a scale. With your TV loaded pay another $10 and run it across the scale.
Now you have all your numbers on 2 scale sheets. Now sit down and fugure your pin weights and everything else. The next step for some will be shopping for a new dually!