OP - Sorry you had another experience, and glad no one was hurt. Equipment does malfunction from time to time, and with your years of RV'ing - I doubt you are 'get in and drive' kind of owner. I say that as a few posters wanted to blame you for a mistake you may have made. Guys - "Stuff Happens!", so let's not assume the OP is not capable. Sharing this info with us was what boards like this is all about - helping each other.
To me, it's a reminder of just how important the 'pre flight' checks 'and at stop walk arounds' of the full rig and toad are. And, I realized it's been a good two years since I last inspected our CRV's baseplate - will do so before our next trip. And, I've just added baseplate inspection to my yearly maintenance list.
OP - If you do find anything else new to share, please do.
We have a 'hybrid' hook up. Stirling All Terrain tow bar, with Blue Ox knuckles to go with the Blue Ox base plate.
Best to all, have fun, and this post shows - be safe,
Smitty