There's a number of different locks for the coupling, choice is a matter of opinion and pocket.
I used a coupling lock when leaving the camper in a caravan park. When we parked it in the street or in the storage place, I added 2 multi-wire bike chain-things (not made of chain but I don't know the word for it), one through each wheel rim and onto the axle. I also used a padlock in place of one of the shackles for regular towing and street parking.
One of the coupling locks at Super Cheap which I considered just recently is designed to be used to lock the trailer to the vehicle for overnight parking but not for towing.
The current trailer weighs 85kg and a strong person could pick it up and walk off with it, coupling lock and bike chain notwithstanding. I've bought a 'trailer cop' an el cheepo from Super Cheap and another bike chain but haven't put them to the test yet. It's a trailer for camping equipment rather than a camper trailer. Naturally the original set of locks and chains were sold when we decided there was to be no more camper trailers
Mine is insured, if they want it they can have it, there isn't anything in it that we can't replace, same goes for the car, besides if they realy want it, all the locks and anti theft devices in the world won't stop them.
01 Discovery TD5 Locked & Lifted & Redback Country Camper Trailer We swear by the Southern Cross to stand truly by each other and fight to defend our rights and liberties. Peter Lalor
I dropped my friend home at Caloundra after the weekend at Boreen, and her neighbours had parked their boat and trailer right out the front of their house over the weekend. At some point during Saturday night someone has come along and set the thing on fire. Apparently the owners were alerted by a passing motorist, but by that time it was well alight. I've got some photo's of the aftermath that I'l load later. It was a complete and utter mess, but thankfully they were insured.
It's all fun and games until someone gets hurt - then it's bloody hilarious!
Redback wrote: if they really want it, all the locks and anti theft devices in the world won't stop them.
That's so ... ditto for the Amplimesh on the windows and triple-locks on the screen doors at home BUT it stops the casual thief. And casual theft is the most common form, so I hear.
Having something tough to remove securing the wheels to the frame is the way to go. I just use the coupling lock as something which would take a bit more time to remove and just a deterrent to the light-fingered passer-by.