I wouldn't worry about getting permission. There are no fences or property line markings, just follow the roadbed in. If you were to get permission for the other 7 or 8 privately owned parcels you need to cross to get in there, you'll grow old waiting. It is a noble thought and gesture, but not really necessary in this location. The turntable site is not posted, so go in and take a look, from the lower leg--the upper leg is posted, so avoid that.
And there's maybe 3 feet of snow there today on the ground, so it will be around June before you can get in there.