Will you also employee a sway control with the WD hitch? If so be very careful if you encounter slippery roads. A slight slide is nearly impossible to recover from with the sway control engaged.
We haul ours on a 16' aluminum H&H tandem w/brakes on both axels. I don't see a need for a weight distribution hitch. On one occasion we hauled two Ranger XP1000 Northstars approx. 700-mile round trip. With the motor in the back, it really is balanced very good with the majority of the weight...