I think the commercial solutions above could be easily foiled by a big crowbar.
Whenever I must leave one of my trailers unattended, I will pull a chain thru the slots in the wheels to the axle or frame.With my tandem axle trailer I chain both wheels together, or use a very heavy duty cable equipment lock. Either way presents a visual as well as physical barrier between your stuff and the bad guys. I'll also use the cable lock when I have my Honda 2K generator on the trailer under the jeep. But you can't see that deterrent under cover of darkness.
I read a friend's email about leaving his tandem axle trailer in front of his house overnight. He cable locked (1/2 inch steel wire rope with plastic cover) the wheels together on the curb side. Come the morning he looked out the window of his abode to discover his trailer was AWOL! He ran out to the street and spied a pair of black skid marks from locked up wheels wandering down the street. He jumped in his truck and followed the skid marks a couple blocks away to find his tandem axle trailer abandoned right in the middle of the street. Apparently the would be robbers had second thoughts.
jefe
