I'm sure all the aftermarket additions, make a big improvement in handling,but before you spend all that money on parts, get a quality Alignment done. That way your beginning from a stable, and a correct position to add all your enhancements to.
I took our our 17 Challenger 37TB to a Heavy Truck Suspension Shop and had an Alignment done, and was amazed at the improvement in Handling ! It went from White Knuckle, Constant Steering Imputs, to Tracking Straight down the Lane, HANDS OFF ! Overtaking and Approaching Traffic is barely noticeable now ! It also seems more stable in turns as well.
I talked to the Tech that did my Alignment, and he said it was out of Spec pretty bad, which he said was typically what they see in RVs, as well as Road Tractors. He says both are just "Ball Park" Alligned at the Manufacturer. I still intend to install a Safety Plus Steering Stabilizer for front blow outs.
I would also suggest looking at Sumo Springs as a addon. I added them to the rear, along with Bilstines HD to my 2012 F-350 King Ranch when we had a 5th wheel, it made the unloaded ride in the F-350 almost pleasant, and the loaded ride was even better !
Max Shaver Jr.
2017 Thor Challenger 37 TB