I take my three cats for an unleashed walk along the tracks a short way. They instinctively form a hunting party around me as we walk; they treat me like the platoon commander or some such. One is the scout, the senior maintains discipline, etc.
At the first sign of a distant train, they inform me, and we go back to the yard and watch the train pass. They must consider them some kind of mighty, blind worms.
It is not quite the same as a leash-walk through the forest, but I feel very lucky to have a little pocket for the cats to reveal their outdoor personalities in this way.