I don't know but just tagging this thread to see what pops up.
I camped right there on the loop about 25 years ago, long before much of it was fenced off. Took a lot of pictures, all long since gone. Was an enjoyable trip, even getting woken up every hour or so by a passing train.
I took my son there when he was 2 or 3, and he really enjoyed it. A great place to just sit and watch the trains go by.
If you go into Tehachapi, there is a nice park along the tracks on the east side of town, with a good BBQ joint across the street.