Check your tow hitch. If it has 5 bolts per chassis rail then a WDH is fine. I strongly recommend the use of a WDH hitch for any significant ball weight.
Just as a note: if your hitch doesn't have 5 bolts per rail, you may want to take the car to a Nissan dealer. They were inspecting the chassis rails of D40s for defects in relation to towing hitches, sending them off to be welded if cracked, and replacing 3-bolt hitches with 5-bolt ones.