The R4R chassis was a VERY harsh riding chassis. The trailing arms need to be replaced because it's not if they will break, but when. The shock puts too much stress where it's attached and breaks the arm.
The Ride Kit had nothing to do with the trailing arms, it was to improve the rough ride. It replaced the airbags, and the shocks with Bilsteins. The Bilsteins were supposed to be made just for that chassis.
Our friends had a 2007 HR Neptune with the R4R chassis. I did some things to theirs to try and make it ride better. First, adjust the ride height. An incorrect ride height can cause a rough ride. Second, I installed the Koni FSD's on all four corners. Lastly, I lowered the tire pressure, after weighing it, to the minimum pressure. It rode better but was still a little harsh.
Don & Mary
2019 Newmar Dutch Star 4018 (Freightliner)
2019 Ford Raptor