I put a sway control on my 7x23 (18+5) legend the other day. Even with the straight pole hitch it still makes a world of improvement.
Just the cheap $50 one from harbor freight.
Left the farm the other day with it empty and made it 2 miles and stopped to put the sway control on as i had decided against it for a 20 mi round trip, What a world of difference!
What also helps is i got rid of my sloppy adjustable hitch for a normal shank hitch. I slid the receiver in all the way and drilled another hole. The extra 4" closer to the pickup and the loss of slop in the hitch made a world of difference alone.
Thinking about adding a anti rattle device to further tighten the connection.
Thought about hooking directly to the bumper to eliminate all slop and move the connection farther ahead, but it wasn't rated for the load. (and looks trashy)
Another thing that is overlooked is the trailer tires/brakes.
Make sure your brakes are in Great working condition and that your hub seals haven't gone out and filled your drums with grease.
I tried Goodyear endurance tires this year and the stiffness of the sidewall has made a substantial improvement in sway and slightly helped with milage.
Run ALL trailer tires at max inflation pressure regardless of load, You don't ride in the trailer so ride doesnt matter and hardly anyone tows enough to wear out trailer tires before they dry crack.
The overkill weight rating and 87mph speed rating also is a good piece of mind.
Also use a good name brand SYNTHETIC grease and Japanese or USA bearings. (not china)
This all sets you up for trouble free towing.
2017 5.3 1500 CC 5.5 with 10 ply tires a level and rear bags. (bags are not needed but help)
The whole setup is at the max of what I feel is responsible load to take cross country and don't expect to run 80 the whole way but it can be done at 70.
But 80% of the time we will take my buddys 6.7 powerstroke.