I would get some 0.5 inch thick steel plate about 6 inches wide and bolt to frame cross wise. Get what ever else you need to go across the frame and bolt on as needed. Then get a hitch as wide as you can and bolt to the cross wise pieces you put on. Make sure you use width adequate for weight and bolt with appropriate bolts. So you span the frame cross wise with 2 or three appropriate width pieces and then bolt hitch of the right capacity. If there is a slant to the frame make some spacers with thick washers or cut steel pieces to level the hitch. I have not looked under my Vegas 2016 to see exactly how the hitch is bolted on. I would not stop until I had the capacity or higher than you need to tow Wharton you need. Your steel supplier can give you the cross prices as you need. Years ago in Canada where I lived I had one heavy duty hitch( a Class 5 ) and used it on three or four trucks I had that were all heavy duty and attached the hitch as I have just explained. I never had an issue towing. Having things stronger than you need will not hurt!