You could make one to mount on the stock bumper, but the thin material on the stock bumper is not structurally strong enough to support the weight and twisting force of a spare tire and carrier. You could come up with bracketry to connect to the rear crossmember, and then make some frame tie ins to go between the crossmember and the framerails, but by the time you do all that, you will probably want a bumper with more clearance that doesn't dent and bend easily.