I think you should install multiple cameras on at least one tractor, powered by the tractor battery and running all the time. While you are using the camera, keep it sending pictures to wherever you can send them. The reason? Sooner or later someone is going to pull out in front of you while hauling that tractor, and cameras from a different angle besides your dash cam might be just what you need. Plus, if they are always online, you don't have to spend time setting them up. Whoever is doing the damage is very likely to see you setting them up, and act accordingly. You don't want them to know the cameras are there, or they will break into wherever they are to destroy them. Most likely, you won't have to run them more than a few months, because if they are good cameras and take good pictures, and well hidden, you will catch your culprits. Once they are caught, and you prosecute, word will get out. Won't be much need in keeping the cameras active after that. (but I would if it is not cost prohibited)
Most likely a couple of cameras on one tractor should be able to pick up enough of a wide view to catch someone approaching. Might require a little thought on how you park the other tractors around it, to give the cameras the best chance.
The semi truck I drive has cameras rolling all the time, and the images are constantly being uploaded. If something happens (I had a chicken run out of a yard all the way to the road and nail my truck in the side of the sleeper). I was driving 30mph and saw the chicken coming. I called safety and they backtracked about 5 minutes to watch it on video. They couldn't believe it once they saw it.
As far as getting multiple angles without having more cameras, consider adding rear view mirrors in the path of the camera. My forward facing windshield camera can see both front fender mirrors and has viewed several instances where people were caught trying to get into the truck or fuel tanks.
David from jax