Gosh, so many adapter manufacturers and so many users. What is really structurally different about the new Goosebox from other adapters?
The O4 3670 Montana Big Sky parked two sites away from me RIGHT now in IN has a Gooseneck adapter. He's been to Spokane WA and Central TX from his home in eastern IN since he bought his Fiver NEW using a Colibert (very commonly seen adapter). I've been towing my 05 3670 Big Sky since 07 with the STAR Performance Kingpin (Gooseneck adapter with a built-in glider to reduce stress/chucking) successfully (survived even hundreds of miles last week on I-65 in IN - the roughest Interstate I've encountered in years).
Based on my long ago study of statics and dynamics and the ongoing experience I've had with an adapter (sorry, no strain gauges/testing), apparently the increased forces (if any) are very small and do no harm, mostly due to the solid nature/construction/installation of the adapters which prevent "moment arm" / torque movement or rotation as some believe must occur, but in fact cannot under normally encountered conditions.
Very rarely visit a Campground without one or more other Fivers with Gooseneck adapters.