I have done a LOT of towing over the last year, and I have to say that the hitch on the trailer I bought is one that I think is the best available for being secure to the tow vehicle. Once it's latched, it's almost impossible for it to accidently unlatch. Even then, being paranoid, I use a trailer lock that makes it impossible to unlatch it accidently.
Here's a vid on the version I have. Once that lever goes over center it's very secure.
Even then I use this collar lock which makes it extra secure and theft proof.
The trailer is made by PJ, and they also use some pretty hefty safety chains with snap hooks on the ends. I have to say I'm danged happy with it.
Here's a pic I took before I bought the collar lock, where you can see the safety chains.
The ONLY way this puppy is going to break loose is if the hitch assembly parts company with the tow vehicle.
That is the best couple ever designed. I had the back end of my Suburban completely off the ground when I was loading a tractor. The couple held tight.
A couple of years ago I took Christine down to the scrap yard with the little trailer on the back. When I left the yard I noticed an odd noise and I got to where I could pull over and look. The nut on the hitch ball had worked loose and fell off when I touched it. We had towed that trailer about 100 miles the day before. I limped up to a garage and we got the 1 inch impact after it. I don't even know if I could get it back off now.
The safety chain on my big trailer with the pintle hitch is big enough to lift a bulldozer with. I have no idea who put it on there but it will defiantly hold.
My biggest trailer pet peeve is people not securing their loads. I see it all the time when someone comes into the scrap yard and stuff is falling all over the place. I got about $40 in aluminum sheet one day just following a guy to the scrap yard. It flew off and Steph would jump out and grab it. There is one guy who tows vehicles in all the time on a flatbed trailer with no tie downs at all. He put them in park and tows them. I have seen them almost off the back of his trailer when he pulled in.
Another guy pulls them in a rollback with only the winch cable holding them on. Nothing on the back of the vehicle at all.