When dealing with the lite model FWs, the axles/springs under it can make the GVWR vary by a lot. You can have a CCC from 1,500 to 4,000, in which case, using the 23 percent of GVWR may be farther off than the dry wt. A little understanding about RV axle ratings, including tire capacities will help, when buying new, and can't use the scales.
Bill is right, good to know what is available on trucks rear axle, to better know if you can handle the pin wt of a particular FW.
BTW...some folks spell Cummins right, but say cummings when speaking.
Jerry