To stay with a SRW, you may need to go to 19.5" wheels in order to get sufficient tire and rim capacity. These commercial tires do well on varied terrain except for places where you need flotation over the media on the ground since they are much stiffer and require higher minimum tire pressures.
Suspension upgrades you should be reviewing are upper and lower Torklift StableLoads, Helwig or Roadmaster rear stabilizer bar (if you don't have the OEM) and heavier dampened shocks from Rancho or Blistein. If the StableLoad setup is insufficient to keep you level, you probably also need the wheel upgrade and will need to decide how much you want to modify your current truck or whether to start over with a larger one.