My experience was with a Ford Excursion and a 36' TT. When we put too much weight on the rear then it swayed, bucked and porpoised. It sucked to drive even with WD hitch and a sway bar. Learned my lesson. Put more weight up front (a visit to the scales is a good idea). Ride also improved when I added a second sway bar. At 30' two sway bars might be a good idea.
WD = weight distribution hitch. Two arms (in the shape of an "L") are added to the hitch in a manner to increase the weight placed on the front of the TV.
To answer your original question. We went to a 40' fifth wheel and dually. It is a 100% improvement in highway stability over the TT even with two sway bars and WD.
The physics involved with a fifth wheel make it inherently more stable.