Need and want are two different things. Being a DRW doesn't effect weight transfer and ride, and with only 1370lbs of TW their isn't much benefit to the slightly stiffer DRW suspension over a SRW 3500. The biggest benefit is the DRW is less prone to sway from an improperly loaded trailer. So being a DRW in this instance isn't really factored I to WD or not.
The WD hitch will really improve the ride while towing, and restore some weight to the front axle for better steering and lighting.
I highly suggest one, but no it's not "needed".