"It could still be taken apart but it will surely slow someone down."
That part right there is the most important part.
If they want your trailer they will get your trailer. Anything you can do to slow them down might make them pick a different trailer or someone might notice before they can get away. My trailer is at my business in a gated lot with a camera system yet I still have ball coupler lock, pin lock, and cables around my tires. Also there is absolutely no indication of what is inside my trailer other than it has front/back ramp doors. The way I see it is that a huge Doo sticker on the side of the trailer makes the trailer more of a target. People suck. Even if you lock it up and take extra precautions they still will try and steal it.