I have a few options and a couple standards. I pad lock the hitch and have lug nut locks on each wheel. Then if I need more, I have an alpha wheel lock (think car boot like the meter maids put on) and a h/d cable lock I can run through all 3 wheels on one side. Because on the lug nut locks, I usually just throw the wheel lock on. Also, I have two spares mounted to the trailer w/ lug nut locks.