As I looked into this, wheel locks, tongue locks, coupler locks, etc. all have glaring vulnerabilities. Wheel locks can be pried apart or sawzall-ed; people have reported the universal tongue locks being cut with bolt cutters or as was mentioned above, using the safety chains instead; locking the hitch to the coupler means you can lose trailer AND hitch; and you can still steal a trailer if you use a coupler lock with a smaller ball.
Then it occurred to me: I can run some
5/8" grade 70 chain through the holes in one of the wheels to the same to the other. Costs about $7 a foot but is
neigh impossible to cut with standard bolt cutters. Would have to dip them
in plastic (or maybe, slide them through flexible tubing, or use Gorilla tape) to cut down on rust on the wheels. Would need about 10 feet of chain plus a
Abus Diskus round padlock.
Can't ride with it in place, can't access the shank with bolt cutters, can't take wheels off (would have to take both, and then how do you pull it?), and the padlock is drill-resistant with unique keys. This should deter 99.44% of theives. Bonus: They also act as wheel chocks.
Pretty much if someone wanted to steal it they'd have to take both wheels off and put new ones on, and if I really wanted I could get some of those specially-keyed lug nuts. (I probably won't go to that trouble.)
Though I've got to decide if the cost, about $160, is worth it. There are meth labs nearby but it'll be parked inside a fence most of the time, and it's not a very expensive trailer. Still, I really would not like to start over totally from scratch, and I will be going to other places not inside a fence. Also I have to see if the chain will fit through the holes.
We all agree though: If a theif really wants it, they can get it.
Thoughts?