There are adjustable shocks as well as spring-overs that help with body roll. Most anything to do to control body roll will result in a stiffer ride
The panhard bar has nothing to do with body roll control. Although without one your truck would be all over the place wiggling down the road
. They serve to keep the rear located, since only having coils would obviously be highly unacceptable.
For the rear, there are sway bars as well. But I would suggest Air Lifts inside the coils. Fully adjustable for firmness and ride height to a degree. They are highly effective and last time I bought them they cost $80-90. Multiple benefits with those