Chucking is a problem we all face, not only does it wreak havoc on your trailer frame and its contents, it makes for a bad ride in your truck. If you like to drink coffee while you drive, good luck, you will spill more on you than you can drink. Your wife will be grabbing the hand holds and looking at you like you can do something about it. And you can't do anything about it. Thats on interstates, it gets worse on state highways and county roads
But there are excellent solutions to stop this problem. But you should decide now how you want to approach it now. It's expensive to change horses in mid stream.
The first question is what kind of pin box does your perspective rig have on it right now? If it is a solid stock pin box then you must address the problem, if it has a special pin box on it already you might be able to have it removed or if you like it you can just keep it.
But lets say that you have a stock steel OEM pin box and you want to eliminate the chucking problem (take my word for it, you have a chucking problem) you can buy the Reese hitch and a special pin box designed to eliminate much of the chucking problem. OR you can buy a hitch that eliminates much of the chucking and keep the steel OEM pin box. You dont need to do both. Although some have.
I dont have any experience with the Mor/ryde or other pin box products, but others do and they will see your post and get in on the conversation, there are many pin boxes designed to manage chucking. Some more popular than others.
The Trailer Saver BD3 is a 18000/3500 hitch designed to eliminate much of this problem, with this system you just keep the stock steel OEM pin box, everything is on the hitch. What I like about teh Trailer Saver BD3 is; 1) Once you buy it its yours, you won't be kissing it goodbye if/when you trade your rig. 2) It works, and you need do nothing except to install it. 3) it breaks down into pieces making it easy to handle. Major drawbacks are; 1) It's more expensive. Not so much for a new installation, but changing to it after the fact is hard on the wallet. If you want one, buy it now, its not so difficult to take the price difference at the onset. You can buy them in new condition off of craigslist if you keep your eyes open, start looking and you will find one. Perhaps the good folks over at Trailersaver have a rebuilt one they will sell you. Another drawback is it effects your payload. Compared to the Reese without a slider and a Mor/Ryde, the Trailer saver is 3 lbs heavier, when adding the slider to both systems the Trailer saver is 17 lbs heavier. It is just a thought, payload evaporates quickly depending on your truck. If you are close to being over then maybe it is a consideration for you.
Anyway the chucking is the problem that you need to cure, but you should figure it out now because you will have to live with the decision you make for a while.
Good luck
I'm completely oblivious as to the combinations you suggest. I believe the dealer is suggesting a Reese 16k. That's all I know.