Just as an aside, and it won't help your situation at all, but, if I've correctly identified the hitch from the pictures, I have very negative experiences with that particular hitch, the Reese Pro 16000. It has little to no side to side pivot capability, which might have been important in your situation. From the looks of the hitch now the clamps certainly look deformed, which indicates the kingpin was indeed latched and pulled its way out, but I'm no expert on hitches. But my point is that I do not like that hitch. The mechanism is not robust. The little groove in the handle that supposedly locks the clamps around the kingpin by keeping the handle from coming back out is insufficient in my experience. Under the right pressures it apparently can pop out and the latch mechanism release. I am sure many people have okay experiences with the hitch, but it doesn't have much side to side motion (it has no side to side pivot, only front to rear), so if the truck and trailer get in a strange angle in relationship to each other then all the pressure is on the kingpin/latch clamps and they can let go. If it had a side to side pivot point then hat would greatly relieve the pressure on the latch mechanism itself. I bought my trailer from my friend who had that hitch, and my first purchase was a hitch that had both front to back and side to side pivots. I know people who have dropped their fivers twice over five years with that hitch.
