Just weld a ring to the back of your subsoiler foot, tie a 3-foot piece of rope to the ring, tie your UF wire to the other end of the rope, and plow away. I've done it many times. You will have to make a dry pass or two to loosen up the ground if you're using a small tractor.
You will be amazed how little drag actually develops along the wire. It makes its own little tunnel through the dirt and on runs of a few hundred feet you can often pull it by hand through the dirt after you untie it.
Same method works well with PVC pipe.