Many people purchase a 27'-29' 5th wheel with the assumption that it will be easier to tow. This is not always the case. The main benefit of the shorter unit is it's probable lighter weight and it's improved maneuverability. But that's probably where the benefits end. If the heights of units are the same, then wind resistance while traveling is no different, which is a noticeable factor of towing.
What is interesting is that experience reveals that much of the time a shorter unit will actually "pull" harder than a longer unit. It's probably the same reason a longer wheelbase crew cab truck will ride more smoothly than a short wheel base model. The greater the distance from the hitch pin to the axles the less bounce and "buck" is experienced. That is why we hear some customers on the RV forums ask why their small 5th wheel tows worse than the longer one they owned before. An extremely light unit will most likely add "bounce" to this phenomenon.
What's the solution? First of all don't buy short for the purpose of obtaining a better ride; you may be disappointed. Secondly use something like our Demco hitch pin box to "dampen" the bounces and jolts caused by rough roads. Adding MorRyde or Trail Aire to the trailer may help, however we don't always find this "fixes" the true cause of the problem. There are certainly benefits of buying a short trailer, when the livability fits your individual needs, but don't assume towing and ride, or even fuel economy, will be any better than buying a unit one or two feet longer.
This question is also available for viewing online at http://www.nuwa.com/faqs/questions/24/