Don't know what to do?

I also need to understand what is meant by GVWR. The 5th Wheels I see have like a dry weight of 11,720, a GVWR of 14,000, and a Hitch weight of 2,010. What do all of these mean? I can understand cargo weight is added stuff, like your belongings underneath like storage stuff, your pots and Pans, dishes, washer and Dryer, all the stuff you bring into the RV. What about gray water, fresh water and Black?? Are those added in the cargo or are they extra on top of the cargo? On a lot of the specs of 5th Wheels they have like 3772 cargo weight. Does that include the tanks?