Well as i have seen this issue before i became interested in trailer security. After researching it i found a wireless system that once installed it would have a shock sensor along with door sensors. If the door sensor is breached the siren goes off and the trailer brakes are locked. The shock sensor(if someone was to hook up the trailer) would also set off the running lights and lock the trailer brakes. I have become a dealer for these units and will receive my first shipment of them next week. It is about a 2 hour install job but has excellent instructions and support. For DDR members I will sell them for $305.00 which includes 2 door sensors, siren, 2 key fobs and the alarm unit. If you have more than 2 doors that you want to alarm the wireless senors are $53.00 each or you can get a hardwire one for $10.00 and it is a simple wire set up. I will be installing this unit on my trailer and would be glad to demonstrate it. If anyone is interested let me know.
Terry