The Weed Patch was originally built by some locals who called themselves Team WTF. Nowadays most people know the area as the San Clemente Singletracks or SCST.
Originally a set of illegal trails, the California State Park system adopted them into San Onofre State Park and with help from the locals, added signs with area maps to officially designate the now legal trails.
Navigating around this area is fairly simple. Southeast of you is a fence that runs parallel to the San Mateo Creek and the Camp Pendelton Marine Base. As long as you don’t cross through any fences or marked no trespassing areas, you’ll be fine and most of the trails are loops. One exception would be a trail leading off northeast to the power station. Once you reach the power station, you will need to turn around.
Also, note that the fire roads around the golf course (access roads for the power lines) used to be open to the public, but sometime in early 2010 they put up no trespassing signs.
This bottom to top option gets all the climbing out of the way quickly.
(2 miles of climbing with 800′ of elevation gain)
Weed Patch via Wall Street
One of a few short but very steep and challenging climbs:
Photos of San Clemente Singletracks