Fluid balancing the tires is just a good way of making sure your get driveline vibrations. Not to mention it adds weight to already heavy tires. Being a fluid, it will settle to the bottom each time you stop..... I drove a truck that had that stuff, and REALLY didn't like it.

In all reality, it's a big, heavy, truck. With big, heavy tires. It IS going to give a harsh ride. (except when loaded. ) Really not much you can do for it. Better shocks will control the heavier tires better, but, won't give you a more comfy ride.