The last time we checked in there was no one there to sign us in or take our money. The next morning someone showed up shortly before we were getting ready to leave. Many kids were using the park as a shortcut to/from school. We may just be hitting them on their bad days but the place did not feel too secure. We stayed at the Pemex truck stop back on the highway after that.
I know people do store their RV's there while taking the train and have not heard of any problems so it is probably fine.