I have always had trouble finding a wrench big enough to tighten my axle nuts, but after working at the dealer for 7 months now ive figured out how they do it. With a socket, a home modified socket is all. Keep in mind that your left hub has to be off to do this, but its probably off anyways if your needing to tighten these things. You simply buy the properly sized socket, 50mm i believe, and then cut it in half at the base of the hex. Then look around until you find about 18 inches of 2 inch tubing. Coincidently 50mm is just under 2 inches so this tube works perfect. The final step is to weld the new tube section into the middle, where the socket has been cut. This way you can either use a torque wrench for the proper tightening, or an impact if youre in a hurry.
Once i view the service manual at work I'll verify the nut's size, as well as the torque values. Also, measure your axle for the amount of tubing needed, if youre running a wider axle my measurements will be no good. Good Luck.