It's day use only. There is a campground just a short distance away at Rancho Jurupa county park. there is a bunch of folks that take the short hike up to the top and celebrate the new year every year and they mostly come from the camp ground there. And they have an annual easter sunrise service there. Other then that the only folks who "camp" on the hill are the local homeless who periodically get rousted out of there.
http://www.riversidecountyparks.org/locations/regional-parks/rancho_jurupa/
http://www.riversidecountyparks.org/locations/regional-parks/rancho_jurupa/