Yes, a WD hitch would allow the proper balance assuming it is set up correctly. As far as the true weight, you could see if he would mind going to a truck stop to get it weighed, with you paying for it. Or look up that model online and see what the manufacturer says it weighs. If you are confident in the weight on the title, use it. You would think that number would be correct (or close to it), but then it again, it a gov't agency!
I towed a 30' Jayco with mine, albeit for only 8 or 9 miles, and the WD hitch helped keep everything level and in control.
I would also consider adding an electric brake controller. Tekonsha Prodigy's are great and wire into our trucks easily.