My 3 axle Carriage has factory installed Mor/Ryde 4000 RE - it really works well compared to a conventional equalizer spring ride, making the suspension “semi independent” kinda...
Both my irrelevant old Dodge (2006) and Kenworth have pretty soft riding full rear air suspensions so I have not gone beyond the Mor/Ryde rubber sheer spring action pin box. It really settled down the chucking when towing with the pickup. The KW weighs almost the same as the trailer so there is evidence in the dust in the slide area of the pin box of fore and aft motion it is not felt much in the cab.
On today’s roads you cannot isolate fragile loads and interiors too much ...
