My brother had a Rockwood TT with rear bunks (don't know model but it was ~ 34' long or so and I think a 2006). He tried JT's, reinforcing the stock cheap stab jacks plus a couple of other complicated gadgets things to get rid of the rocking and never succeeded. I know that the RV's that you're talking about are very different units but my point is that I think it's in the design of the particular rig. Where are the axles located, what kind and/or type of tires (heavy duty or light duty), what kind of stab jacks and where are they located and how are they mounted, what kind of wheel chocks - he used the plain old wedge style (we use Roto-Chock which "locks" the tires together and sadly are no longer made), etc.
2013 GMC Sierra 2500DH CC, 4x4, D/A
2016 Forest River Vengeance 25V TT/TH