Well first off if the trailer actual weight is 6450lbs, then when loaded for a trip with propane, battery clothes, food, cooking utensils, towels chairs and anything else you will likely bring will put you around 7700lbs loaded for a trip. too much for the 4.7L.
And the weight on the bumper is for the bumper itself, the hitch has a different rating for WD hitch.
either bigger truck or smaller trailer. if you want to keep the trailer below 6000lbs then look for a trailer with a dry weight of 4500lbs.