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.
"After the first glass, you see things as you wish they were. After the second, you see things as they are not. Finally, you see things as they really are, which is the most horrible thing in the world."
--Oscar Wilde on Absinthe