It is not likely that your actual payload is 1,200 lbs exactly. That seems a rounded off number. To do it right, you need to weigh your vehicle full of fuel, passengers, and gear. That total weight subtracted from your GVWR will ensure actual payload.
You should also get separate axle weights. It appears you have a 3,900 RAWR. Most of the tongue wt will be added to the rear axle. If your rear axle, ready to camp wt is 2,900, you can add up to 1K of hitch wt.
Your tires should handle a bit more than RAWR, but look at max tire rating, and also max inflation on sidewall. You will want to inflate tires to more than indicated on door sticker, the rears possibly to max pressure.
Jerry