Garry, We did the same thing, headingout of Cooktown, towards Lake Field National Park (Cape York) last year with with SteveandViv. Travelling along a dirt road, hit a wallow and the hitch came off. I was looking in the side mirrow at the time, yelling to the wife, ahhh $h1te, we've lost the camper. One of the chains held, the D shakle broke on the other chain. My daughter found the D shakle about 100 metres back up the road. A jack and a bit of muscle had us back on the track.
On reflection, I recalled, being pulled away from the trailer, when I was hitching it, not closing the lock. The wife was suppose to do a 360o check, but didnt. I was suppose to do another check, but failed. I believe it all happened in the excitement. It wont happen again.
A photograph of the CT on the ground.