I am going to pick up am new travel trailer on Monday , I did order air bags form the rear but I wont have them by the time I go to get the trailer. The trailer is about 5000lbs and the hitch weight is about 500-550lbs. I will be hauling it empty as all I'm doing is taking it home. How much sag can I expect from this, I just don't want it to be lower in the back than the front like i see so many trucks sitting. I do have a weight distribution hitch with sway bars but it has never been on this truck and ill need to install it on the trailer and try to set it up at the dealer. Truck is a 2015 hemi, 3.92 rear, crew cab with 6.4 bed . I checked my options list yesterday and it has the class iv hitch, I just see the rating on the receiver , what's it good for?