Being in your exact situation, I've done similar. Beefy chain through wheel and around axle/leaf spring. The secondary thing I've done is the off road hitch. Everyone has a 2" ball...few have a off road hitch. Third thing I've considered is a chain to an object in the driveway, when available.
If someone wants it...they'll find a way to get it...but I assure you it isn't going to be an easy smash and grab as it sits and that's the best reasonable thing I can go for right now.
If you're still concerned, up your home owners/renters insurance to cover it appropriately should it be stolen.
Also, to address others...I grew up in a small town. The type of town where my parents didn't own keys to our house so it was never locked. You could go to the store, run inside and grocery shop for 30 minutes with the car running outside (to keep the AC on, cause it was HOT) and you'd go back outside to find your car still there. It was worry free. Few places are like that still. I've been robbed, had the house broken into, etc. It's sickening and I wish to this day I was armed and home. Thief's are people who keep us paranoid instead of just living. Do a reasonable job of protecting your trailer and know if someone steals it, they probably would've taken it no matter what your measures were. Just don't let it be too easy for them. Outside of that...live life and don't make it something that takes away from the joy of life.