The closest tent camping to Six Flags Magic Mountain is at Castaic Lake. Online camping registration is available through the link above. In addition to tents, the lower lagoon accommodates travel trailers and RVs.
Castaic RV Park Reviews
Castaic has the closest RV Parks to Six Flags Magic Mountain and Universal Studios. Six Flags Magic Mountain is 10 minutes from Castaic, and Universal Studios is only 35 minutes straight down I-5. See map here.
Castaic Lake RV Park
31540 Ridge Route Road, Castaic, CA
Valencia Travel Village
27946 Henry Mayo Drive, Castaic, CA