Its not a grand design problem, its a Lippert issue - only seeing it on the larger/heavier fully body 5th wheels (Solitudes and Momentums). The reflection line frames (which I have) seem to be ok so far
From what I have seen, you are probably mostly correct. BUT, the manufacturer still designs and specs the frames, or, even on the low end they approve the frame design.
I've worked a few cases professionally regarding vibration and related issues within the transportation industry and all I can say is that it is more complicated than it seems to the average lay person.


