Had a look online into the GPS security you can get for car / caravan and it was cheap. When looking on the china imports you'd be talking about $100 for the kit plus the cost of a sim card to GPS track the vehicle.
Has anyone done this for their trailer or caravan. Seriously going to look into it with a small battery hidden away somewhere. I have a small 10 solar panel that keeps the battery topped up on the Ct - I could alsoway have this run the two batteries with one hidden.