The question is not about the stationary (static) “weight” value of the trailer tongue. That’s a moment frozen in time. The dynamic of being in motion means the two vehicles are rotating on separate axes most of the time AND that the FORCE on the hitch ball is constantly changing. It may increase to several thousand pounds in one moment to pulling upward by a few hundred or more in the very next. Trailer leaning left and TV leaning right.
The game is at the contact patches of the rear tires.
A WDH distributed the VARYING TW loads across BOTH vehicles. Preserves solo steering & braking “feel”.
The prime risk isn’t weight when towing. It’s crosswinds. Sudden gusts where the driver doesn’t understand how to correct. Over in about 1.5-seconds.
A DRW isn’t any guarantee of safety. They suck, unless — like all other tow vehicles — they have sufficient load in the bed to SHOW tire loads are maximizing the tire contact patch. The more stiffly sprung is a TV, generally the worse it is unless being used to design. An SRW nearer GAWR beats it every time where the DRW is underloaded.
A DRW is what you might want for a GN/5er. It’s the wrong direction for a conventional hitch where the bed isn’t sufficiently loaded.
A WDH makes the combined vehicle react more as a single vehicle. Keeping the TT Under control means increasing the weight on its axles, and reducing front-end rise on the TV. “Weight” is the dumb new-guy thing. Steering & braking ARE improved by use of a WDH.