Weight distribution hitches change the location of measured weights, simply adding this and that will not provide an accurate load measurement that will be carried by the truck. It's a ball park estimate. You can also adjust loads within your truck and trailer to change hitch weight, and the quality and length of the w.d. hitch can change hitch weight. The truck's "tongue rating" probably does not consider the type of load a weight distribution applies to the truck's receiver.
For example, our Airstream factory spec hitch weight is 835 lbs. Our ProPride w.d. hitch assembly is 180 lbs. After loading the additional weight of camping/traveling gear in the Airstream and truck, with weight distribution applied, the Airstream and ProPride hitch add 820 lbs to our truck's weight.
What is the tow vehicle you have in mind, some are much better than others even though factory spec's may indicate they are equal? They are not all equal in performance and handling. Some are easier than others to distribute weight with a w.d. hitch. Some are more stable than others. And how many passengers and how much gear in the tow vehicle will go camping with you?
The information provided at this point is not enough to evaluate the tow vehicle's suitability for your FC 20.
Doug and Cheryl
2012 FC RB, Michelin 16, ProPride 1400
2016 Ram 1500 Laramie Crew Cab 4X4 Ecodiesel 3.92 axles
The Truth is More Important Than the Facts