I have a great very sturdy roof rack so I use it to keep the Dub from rocking fore n aft which is a killer of hitch connections that are marginal. It also keeps the rocking to an absolute minimum. My bumper is aftermarket and quite sturdy compared to the old OEM bumper that has no hitch receiver. If I did not have the roof rack I would not put the Dub on the rear. The weight removed from the front of the Zuke is about 150 lbs. The teeter totter effect ya know.
If I were to do it again I would have invested in a tilting type rack like Skipro's. Much easier to get the Cycle up onto the carry position.