It depends on what the vulnerability to break-ins is : the locks, the bodywork around the locks or something electronic that can be bypassed. Might be worth look what Armaplate sell for that model of vans – I had a set of their lock protectors for a sprinter and a lot of their products are developed to foil the known vulnerability for that vehicle rather than just adding additional locks.
Can work out pretty expensive though. A full set of plates for my van cost over £200 and you can spend a fair bit more than that on getting them fitted if you’re not confident to do it yourself.
Its depending on what the risks with your van are its maybe worth thinking about whether you want to use them pre-emptively or not.
I wasn’t aware of the plates / vulnerability with my van until there had been a break-in. Nothing valuable was taken but the bodywork around the lock was mullered. In that case a plate was the best way to repair the metal around the handle. But given there was no other loss other than the cost of the plates it didn’t matter really whether I’d bought them before or after the break-in 🙂
With a camper conversion the question is are you going to leave stuff visible and unattended in it – if not then people can see in and theres no need to break-in. With a regular van thieves have to break in to see that its empty.