There are no facilities at the Bowen Ranch, but you can camp there and have a fire. I suggest you bring your own firewood. Lumber is scarce other than the local scrub and sage trees.
You're right about camping. It's not allowed at the Springs themselves per Forest Service rules. (The Springs are within the San Bernardino Nat'l Forest, btw.) While some people ignore the law, I would not recommend it. The FS has been known to show up unannounced and escort campers out of the Springs, if not ticket them as well on occasion.
Enjoy!