I always enjoy the "engineering" debates about Goosenecks and usually weigh-in as a thoughtful user.
Besides the physics of levers/moment arms, static and dynamics, there is also "Strength of Materials" which certainly plays a significant role.
Obviously with at least 10 different vendors of Gooseneck adapters and many satisfied customers there can't be a moment arm of 20-30K lbs on a 14K Fiver, or it would be damaged quickly. I have a friend with the same Fiver as mine, although his is an 04 and he's used the "Ranch Hand" adapter since he bought it new and my Winter Texan neighbor uses a similar adapter on his big Fiver.
My Trailer has been STUCK 3 times and I've encountered one Emergency Braking Situation (Truck ABS engaged) years gone by (before 2012) that would have introduced the maximum "instant" loads (albeit slowly) versus normal day to day towing and my trailer and gooseneck survived them so the loads simply can't be too great and certainly don't exceed the strength of the components or damage would have occured then. The only damages I've encountered involved extraordinary (usually repeating) road hazards while towing at speed. The one that broke the frame also disabled my 1 Ton dually and bounced a 20 lb Kitchenaid mixer out the sink (a first)!
While we were stuck in Dallas for almost 3 weeks getting repaired, the news had a story on how so many Pothole damage claims for autos could lead to higher insurance rates for victims. The direct road from our Campground to nearby Siegleville TX was so bad we usually took an out of the way route that added 8 miles to the journey. Not all roads are maintained equally.
I still enjoy the free bed space, impossibility of dropping the trailer, and gentle raising and lowering the RV to hookup or disconnect. Lining up the ball sometimes takes more than a few attempts and hooking up safety chains are complications.
Safe travels!
