Don't know if anyone has done this already but if you have an old iphone laying about you don't use ,you can make yourself a cheap tracking device out of it. I have an iphone 5 with a cracked screen and have just set it up as a new phone and called it Van Tracker ( original i know ) and then deleted every app i could from it ,turn off everything you don't need and turn the screen brightness right down.Then i bought a usb socket off Ebay for a couple of pounds and wired it up in the van " somewhere" you can do a permenent live or wire to ignition depends on how much you use it . then plug the phone in on the charging cable and mount it so it can't move about and then use the find my phone to locate it . The battery lasts a long time on standby and if your pride and joy gets nicked at least you will have some hope of finding it. With find my phone you don't need a sim card but you could put a pay as you go sim in and set the phone to auto answer so you can perhaps hear a name or a place being said by Mr scumbag as he drives your van away .