Use a angle iron that reaches from one side to the other where your bumper brackets are together. Use two old connecting rod caps, drilling the angle iron for them and bolt the iron. Use a 1/2"by 3" Flat bar welded to the angle that runs under your bumper, drill it for the ball and weld a flat bar to it that extends up to the top of your bumper and drill a hole thru it and your bumper for a bolt. If you do not want to drill the bumper, you can set up some sort of a clamp.