bounciness in the rear
I think you need to clarify that. Is it too much rocking or bouncing after the bump has passed? Boat like ride? Sloppy? This would point to need for stronger shock absorbers.
Or is it slamming, jolting, pounding impacts on the bump itself? This would point to too much tire pressure, or too stiff a shock absorber. Even under normal circumstances ride in the rear can be worse than typical vehicle. Possibly over the rear axle or cantilevered out behind it.
I noticed a slight vibration in the steering wheel at speed above 70 mph but it's not always present.
Have the front wheels re balanced. It could be a few other minor things but my bet is on that.