The old boy scout camp is located near the Terresita Pines Lions Camp swimming pool. Just East of there, along the Mescal Creek by an old fire road.
There are no buildings left there, just some foundations. It was gone by the late 1960s when I first hiked by there, and I heard that it was washed out by a flood, possibly in the 1950s.
The camp across from Appletree was know as "Camp Metaka" and was some type of Girl Scout camp, Bluebird/Camp Fire Girls camp. Across from Arch campground was known as Camp Centenilia. Both of those locals also sport some concrete foundations.
Your Friend,
Bill Lussenheide