I have looked a lot at security over the last year or so and it is something I am fairly obsessive about as I have a Hobby caravan which tend to be stolen far more than other brands.
I am probably going to go against what most people above have said! As someone who does a bit of metal fabrication for a hobby and have a reasonable amount of basic equipment, I can remove every single one of those security products mentioned so far in minutes, if not a lot faster. And relatively quietly too. Sold Secure testing does not include oxyacetylene. Opportunistic thieves may not carry this, but every "professional" caravan thief will carry oxyacet and it will make very light work of every wheel clamp, hitch lock, post, chain etc. It is exceptionally effective at cutting metal, cheap and quiet compared to angle grinders etc (which incidentally will also remove any of those products, but will take longer on some and will create a lot of noise).
There is only one lock on the market that is effective and cannot be removed with oxyacetylene and this is the JSB Hublock. To date, there has never been a caravan stolen with a JSB Hublock. The design is a very very solid and heavy chunk of metal that bolts directly to the hub. In theory you could eventually get it off with oxyacetylene but to do so would generate so much heat in the hub itself that the hub would be completely destroyed. People who have not used the JSB will say its easy to get off by targeting the security bolts on it. That is not true - not because the security bolts are anything that special (they are off the shelf McGard bolts albeit a slightly different model to more commonly used ones). However, they are very deeply recessed into a narrow chamber with no lateral clearance that makes it exceptionally difficult to remove them. Professional tools such as Dynomec locking nut removers do NOT work due to the design. You cannot hammer a bolt over them and you cannot even weld a nut onto them. Again, I guarantee you that I could remove locking nuts off a wheel, but not the JSBs.
There is a downside of the JSBs and that is the wheel on one side needs to be removed to fit them. This makes them more inconvenient to use and will put a lot of people off, especially for touring. However, with practice and the right tools, it is not difficult to fit them. I can put JSBs onto my twin axle Hobby (so I have to fit 2 x JSBs) in about 6 minutes without rushing and that includes jacking it up. A single axle would probably take me little more than half that. With every day wheel wrenches you can add about a minute onto those times (typically I use battery impact gun for the wheel bolts and battery drill for the locking nuts). Using a Kojack jack makes jacking up very quickly and easily. I always use JSBs even when touring. If you didn't fancy using when storing, then use them when the caravan is in storage or on your driveway.
The other thing is that some insurance companies insist on a wheel lock and hitchlock and therefore are not content with you having JSBs even though they are the best security product out there and are Sold Secure approved. My insurance company (Towergate) do insist on them so therefore, for a wheel lock and hitchlock, I use the the cheapest Sold Secure product - I have no faith in them whatsoever but I want to be sure my insurance is valid.
If you are not convinced, give Kenneth from JSB a call - he is passionate about his product and will give you all the stats. I have absolutely no connection with JSB, but am just a happy customer.
Also, consider a good tracker and alarm. They will not stop your caravan from being stolen and a wired one can be found by the thieves and removed fairly quickly, but a decent product such as the Outsmart the Thief will have alerted you of the attempted theft before the thief has had a chance to remove it. In fact it will have alerted you before he/she has even heard the alarm. Again, if you want info, call the company owner - Carl Meyer at Outsmart the Thief knows so much about caravan security and not only makes and designs the product, but also is involved in recovering stolen caravans and can tell you all the tricks that the thieves use.
I would highly recommend you phone Kenneth (JSB) and Carl (Outsmart the thief) - they are both small companies and these individuals will answer the phone. However, I warn you, both of them can chat, so put aside an hour or so! However, neither are pushy salesman, just passionate about security and their products.
Sorry, that was a really long post but I am fed up of hearing about stolen caravans and you are buying a very nice and unique caravan that could be a more of a target for thieves. I am in the same situation with my Hobby.
Here are the websites for the products I mentioned:
www.jsbhublock.co.uk
www.606060.com/
I really hope this helps
Ben