i know of a small place off of HWY 50 E. you take the Cameron Park exit and make a right at the end of the ramp. then take the very first left at the light and go down until you hit the dirt. I'm not sure if it's legal exactly but I've been there lots of times and I've seen plenty of people out there as well.
In fact, heres a video of me spotting my wife on one of the more difficult spots out there;