TorQ, nobody really answered your question, so...
A gooseneck trailer is pretty simple. Just look at the larger utility trailers or stock trailers you see. That type of frame, that hooks to a ball in the bed, is a gooseneck. A fifth wheel frame/hitch is what you see on most any semi-truck. Think of a lowboy trailer with a box built on top, clear over the king pin and you have a basic FW RV. The problem occurs in the pin box area of the FW. You've probably used a cheater on a wrench to move a stuck nut/bolt, so you should understand the torque that lever gives you. Look at a FW pin box, especially an extended box, and you've got a lever arm sticking out and acting on the internal framework. THIS is where the frame breakdowns typically happen, right around the pin box, but they can also twist the supporting cross-members to the point of breaking out at the side frame rails.
The other thing that can happen in the front area, is that the screws anchoring the house framework either break, weren't installed correctly or weren't installed at all. The "house frame" is structural and, if it's not securely fastened down, the main frame looses a lot of its structural strength, so you get flexing in the area of the dropdown step. A sign if this is, usually, cracking of the sidewall around the bedroom slide (if any) or right at the drop. You'll also likely see the caulking cracking or actual separation of the sidewall from the lower frame.
Lyle
2022 GMC Sierra 3500 HD Denali Crew Cab 4x4 Duramax
B&W OEM Companion & Gooseneck Kit
2017 KZ Durango 1500 D277RLT
1936 John Deere Model A
International Flying Farmers 64 Year Member