There is a possibility the current power line road 20 years ago was corduroy but I would suspect the stones that are there now were always there to allow the huge vehicles needed to get into that area and build the towers. There is a possibility that the corduroy road he visited may have been the original road that crossed the river. If he drove up onto the dune and headed toward the swamp he would have found the original road.
The original road in 1940.
In 1956
In 1965
In 1995 about the time he would have been there.
This road would have had to either had a bridge or pipes, or have been corduroy in the area my arrow is pointing to. The water flow would have been the same as there is now crossing the power line road. There is no way that original road could have just been driven through without some sort of way across the water. It looks like a large road built for logging. It would be interesting to walk that route one day and find out for sure.