You are allowed to camp in the general area. The general restrictions are that you must be at least 200' away from any water source. I just checked the forest service website and I could not find any more specific restrictions listed for that lake. I'm not sure about weekends, but weekdays, the parking lot is pretty empty.
"So I was sitting in my cubicle today, and I realized, ever since I started working, every single day of my life has been worse than the day before it. So that means that every single day that you see me, that's on the worst day of my life."
--Peter Gibbons (Office Space)