Just some random thoughts/experience hauling/towing, GAW, GVW, GCW, SRW and DRW. In my 50 years of hauling commercial and personal, I have never had my Cab sticker, axle or tire capacity questioned or checked. For the most part, I don't even think about any of it, just do my thing. Some times you better be under the ratings, other times over.
Case in point: 2014 Ram 4 door, 4x4, top of the line 1500 Eco-Diesel. They have an 800 lb pay load. I would have no problem loading up 4-200lb guys, dumping 800 lbs of gravel in the bed and driving the speed limit coast to coast. I am double the specs.
If you are towing with a gooseneck or fifth wheel, you can exceed the specs, SRW or DRW without much drama. Bumper pull, different story. I would not exceed the loaded weight of the SRW tow vehicle with the towed vehicle. Dually, you can up that some.
Tow bar towing. SRW, you better keep the tow vehicle way heavier than the towed vehicle, DRW, is way better here.
Now, hauling as a stand alone vehicle. Here your rock solid dually can become a wimp. Take a new 3500 Ram dually, rated for 14k GVW, install a flatbed/stock rack combo on it and try and haul 7 cows. You will only do it once. Yet, you can haul that same weight on a gooseneck or fifth wheel and not look back.
If your weight is inboard of the springs, (gooseneck/fifth wheel) there is no issue, SRW or DRW. If that weight is outboard of the springs (cows that move, any wide, top heavy load such as hay) different story, the dually is not much of an improvement here.
Nick