To put that much dead tongue weight at that distance from the rear springs, you will need some suspension work done. Most pick up trucks can handle one bike on a carrier with only minor issues, but with a duel carrier there will be big issues.
I use a carrier I hand built that includes a bike shoe on a F150 and I and I use air assisted suspension to make it right.
Remember that your rated tongue weigth on the auto is rated at the ball and the bikes will be at least 3 feet behind the ball and the increased leverage will act to increase the weight factor and thus reduce the rating. YOU WILL BE WAY OVER THAT LIMIT!
Paw Paw