Harsh ride & chucking…please help me figure it out! (Long)

I have a very similar setup. I started with a manual sliding Husky hitch and standard pin box. On occasion I would get chucking but not as bad as you describe.
I replaced the sliding base of the hitch with a fixed base, replaced the pin box with a Mor/ryde, added air bags to my truck and adjusted the pin box so I'm just slightly pin high. I made each of these changes over the last three years. Every change made some improvement.
I still get a little chucking on rough roads but nothing that bothers me.