I am wondering if it's possible to get a jeep/bus from Bar Funivia to Torre del Filosofo if you are not booking a private tour?
It looks like this is the fastest way to reach Torre del Filosofo, but I cannot find any information how the transportation looks like there.
The first post in this thread suggests that bus tickets could be purchased at the same place as the cable car tickets. I cannot find any other website confirming that however.