I would strongly suggest you investigate the new 2008 V-Nose 5th wheels that are are made by r-vision. A very light 6500 pounds for a nice 31 footer and the v-nose will solve the short bed problem as front edges simply arent there to hit the cab and the hitch can be mounted in its proper position as a result. The hitch weight is way below norm, as I recall just under 1000 Pounds. They are also very affordable, some of the best pricing on the market. I was offered one this past weekend at $29,500 CDN (our $ is pretty much on par with the USD now). The V-Nose design actually makes for a classy design inside the master bedroom with curved corners, there is no wasted space either.
This is a new breed of 5th wheels designed for short bed trucks like my 2005 XE Crew Titan.
2008 5th wheel Trail lite and Max lite by r-vision, Google them and enjoy.