What justifies the need for a DRW 1 ton in relation to GVWR, (i.e: 1 lb over, 25 lbs over, 500, 1,000 lbs over)?
IMO non of the above. Other folks have different opinions.
Out here on the road the truck makers GVWR doesn't determine how much load a truck can carry from any legal perspective. Thats what the trucks FAWR/RAWR/tire capacities do and in particular the RAWR is the most important as it will carry just about all of the hitch weight.
Your '11 trucks rear axle/tires weigh 3160 lb which leave them with a 2850 lb payload it can safely carry. The one ton SRW has higher rated tires/wheels and rear springs. The rest of the truck is the same.
The '11 DRW has those big 9350 RAWR. Many DRW trucks rear axle weigh in the 3400-3500 lb range which leaves around 5800 lbs for a max payload. Way overkill for a trailer the size your towing.
Some folks use the trucks GVWR to figure payloads on the trucks rear axle/tires and that OK. Doing so is also safe.
