Take a look at the Anderson hitch. Some people call the hitch a goose neck hitch, but I'm not sure one should call the hitch a goose neck hitch. The hitch is designed as an elevated ball hitch. This elevated ball design dose not add any additional stress to the king pin box area. So the stress issue should be a wash with a regular 5th wheel hitch. The Reese Goosebox is approved by the frame manufacture, as the frame manufacture and Reese are within the same Corporation. Who would of thought?
As you travel around the West you see more and more elevated ball hitches. And to the owners I have spoke to, the elevated ball provide a smother truck ride and a one person removal process so you have a clean bed when needed.