Check this out (trucks below are all 3500 Laramie, 4x4, CC, LB, 3.42 gears, G56):
2012 SRW - payload = 2,074 lbs, towing = 11,300 lbs
2013 SRW - payload = 4,480 lbs, towing = 16,010 lbs (huge jump in payload!)
2012 DRW - payload = 4,439 lbs, towing = 11,000 lbs
2013 DRW - payload = 5,790 lbs, towing = 15,620 lbs
So, although it may not be as stable in winds, the 2013 SRW can technically do the job that the 2012 DRW could do.
Assume: we're towing/hauling within the legal limits of the truck's factory specification.
For the SRW, if you maxed out your trailer to 16,010 lbs and had it loaded properly, your pin weight should be 2,400 - 3,200 lbs (15 - 20%). This leaves 1,280 lbs left over for additional payload which to me seems like a comfortable margin.