DRW will help a little with your sag problem but it won't eliminate it. You'll still need supplemental suspension. Be it air bags, Timbrens, etc. Dually's do have thicker spring stacks and a higher GVW than a SRW but still will need help with sag.
2013 Jayco Eagle 328 RLTS
2012 Ford F250 6.2L 4x4 CCSB W/Air Lift air bags
2002 Coleman Bayside Elite (traded)
Me, Momma and Charles (RIP buddy)
And introducing Sofie!! ;)