My rig is almost identical to yours. You’ll probably never get all of the porpoising out of it but you can eliminate most of it. First, get top notch shocks. Big difference. I added an inexpensive gizmo called StalbleLoad. It fits on the spring pack to engage the overload spring. It can be disengaged when not towing and is pretty effective.
And the last that really gets poo pooed on this forum is a Gen-Y hitch. It comes on it’s own stinger and your wdh head bolts right to it. What it does is isolate the trailer from the tv. It’s a rubber torsion device that gives instead of transferring the bounce to the truck. I don’t know how to explain the physics but I do know it works. A bit pricey at 5 bills and kinda heavy but soooo worth it. Not only has most of the porpoisin gone away, but on small to moderate size road bumps I don’t feel anything after the truck goes over the bump. I can also tell a difference in the trailer. Things are not jostled around so much. The company claims it’s also easier on the tranny because it doesn’t jerk it back and forth so much. Check it out, it’s worth a google search.