Caching_clayton had a very small non-magnetic nano, saw this spot and decided he wanted to hide it here. RosellaTheUnicorn named it and helped with the hide. Bring tweezers. Please rehide as well as you find it. About parking: While it is not possible to pull completely into the "castle" area due to the guard rails, there is space to park safely on the south side (East 130) of the road. Parking on the north side of the road (West 130) and crossing is not recommended.
We recently took a picture of the hiding spot to help us find it ourselves the next time we need to. Caching_clayton has agreed to make that picture available by request as a hint, so feel free to message me if you would like to see it.