Advice for (Possible) Overnight trip to Joshua Tree National Park

Dear Members,
I am planning a trip to Temecula, CA from June 12~20. Since I have limited time, I plan to visit Joshua Tree National Park for only 1 day. Maybe even stay in the park overnight to get some night photography. I don't (and will not) have any camping gear with me...just stay close to the car and sleep in the car. I would like to get some advice/ suggestions on what I need to do to prepare and where to go in the park for best possible pictures. I will be travelling with my wife and son (10yrs old) so we don't plan to hike too long periods. We will also have some friends with us. Thanks in advance.

Thomas.

PS. My initial plan is to look around in the park, scout out a location for night photography and just sit and wait until night comes along....