In reality, there is little that can be done to enhance security.
Locks, chains, or cables? Bolt cutters or a portable oxy/acetylene torch will defeat them in seconds.
Lights, cameras? A truly dedicated thief won't really care.
Wheels and lug nuts removed? New ones are readily available from 6 Robblees, Tractor Supply, Big R Ranch Supply, Walmart. etc.
A fenced storage site with a locked gate and a big watch dog? Again, the bolt cutters or the torch, and something to distract the dog. A sirloin steak, or a squirt bottle full of Parson's Household Ammonia, or bear spray.
A truly dedicated thief will find a way!
At the present time, for me, having my 3 trailers parked out in the pasture in 2 feet of snow pretty well keeps people away from them. In the summer there is very little thievery, so I don't worry about it.