The only thing you can do is make it as slow a process as possible so a bad guy will move on to an easier target.
First install an off road coupler, so a crook with a conventional ball hitch can't attach it to his truck. I use an Aussie Treg with locking pin, but it is now impossible to find in North America. Weld the coupler to the frame so it can't be unbolted. Install a stout hitch pin lock at the receiver. If you don't want an off road coupler, weld on a tough _forged_ ball coupler like the Bulldog and use a quality lock.
Then run a heavy duty cable lock from trailer frame to truck frame, not the bumper. You can wind it around the A-frame and secure it with bungee cords if needed. I really like the Python due to it's flexibility and numerous cable options (up to 30 feet). You can also use this cable lock to secure tools, power equipment or other stuff to the trailer frame.
Be sure to buy the bright yellow lock body, and position it so it is visible but hard to access.
Amazon.com: Master Lock 8401D Python Lock, Yellow: Home Improvement
If you are REALLY worried, when you park and leave the trailer, dismount one wheel and take it and the lug nuts away with you. Remount the trailer's spare tire and wheel inside the trailer.
If you have an additional long Python cable (16 to 30 feet), you can park next to a stout tree or light post and lock the frame to it. Keep the cable high and away from the ground so it is harder to cut.
Since you plan on installing a tracking device, how about an alarm system with motion senseor? I doubt that thieves would ever expect that.
The more stuff you add to secure the trailer, the less likely some creep will be willing to spend the additional time to disable it all.....
Good luck
John Davies
Spokane WA