I should have got the HD Payload option as that includes HD shocks, heavier springs and LT tires (as well as the 7 lug axle/wheels with greater payload and rear GAWR).
But I didn't, so instead got the dealer to install the same shocks as in the HD Payload opt, installed Roadmaster active suspension, and swapped the tires for LT's (Michelin LTX MS/2).
The loaded ride is much better IMHO, and my truck is fully loaded to 99% of its weight ratings. But I would probably like even stiffer shocks. If I had to do it over again it would be the Bilsteins or Ranchos. The adjustable Ranchos seem especially nice.
I believe Monroe also makes some over-load shocks (with additional coils) for the rear only.