I take it that you are using "Factory Dry Weight" as a weight
reference for the Keystone.
I was involved in buying and outfitting an almost identical, Dutchman built, Coleman CTE171E last year, for a now ex-son-in-law, and the actual out the door weight
was over 3300 lbs and, when we had it weighed when loaded for a family of 5, it came in over 4000 lbs, with over 440 lbs on the wd hitch.
In as much as his TV was a newer Suburban with factory towing kit, that wasn't a concern, but it suggests that your changing to an FGRV will result in a lot less weight
, not to mention a significant reduction in frontal area, to tow around.
As you can see in our "real world" weights, factory weight figures are very difficult to get down to, esp. after loading, when they are only like last nights dreams, long forgotten. .