[wingnut60]

Ever since I began thinking about owning a fifth wheel about 8 years ago, it has always been mentioned on various forums that the PW should be around 20-25% of the GVWR. There has to be some basic physical rule that has proven that figure to work in the majority of cases--I would think for the following reasons:
1) If too little % of the gross is on the pin, the trailer will be 'tailheavy' and tend to cause sway or hard-to-control conditions
2) If too much % of the gross is on the pin, then the tow vehicle has to be larger/heavier/more capable to carry the weight
3) Moving the axles forward would result in excess weight on the rear axle and cause (more) tire problems

Probably the best towing situation would approximate the configuration of a semi-truck/trailer combo--the trailers have the wheels at the rear of the structure, not near the middle as a fiver has--but then every one would need an HDT to tow, and the trailer tires would have to be much larger than what is currently in use.

The overall design/construction of a fifth wheel is a total compromise of several parameters that each manufacturer feels will work best for their construction--but all seem to recognize the limitations of what the PW should be to make the fiver towable by the biggest number of pickups that are commonly available to the most buyers.

Just get a truck that will handle the actual PW of the unit you are pulling would seem to be the best solution...

Joe