Travel trailer security - keep it or stuff from being stolen

I spent a year looking for a little 21', tandem axle trailer. I don't want to loose it.

I keep it insured well, but also I have an old Iphone well hid in it, turned on at all times. Sitting idea all the time, I charge it when it needs it.

If the trailer is stolen, the thief will really be surprised when myself and the police use... "find my Iphone" to track it down to where it is.

I pay $10 per month to keep service on the old phone with Verizon towers. (Red Pocket mobile)