Paula Pope was from Sacramento, I've found a 1971 senior portrait for her as well (attached).
I've found a differing story about her disappearance, but this is from 1972 so could have been proven wrong. Story from the Mountain Democrat newspaper:
All is as described on NamUs, except Paula and the group were camping around Ice Lake Reservoir within the campsite. She leaves them as described. However, she apparently hitch-hikes to the Carson City Rock Festival as she said she would, and afterward is given a ride by Sacramento locals Terry Laber and Carol Cooper. They took her as far as Fresh Pond, but there she decided to get out of the car, saying she wanted to hitch back to Ice Lake Reservoir. Laber and Cooper try to dissuade her, saying she should just continue on to Sacramento. But she gets out anyway, and no one sees her again. In a November 1972 article, Terry Laber says that Paula was talking to "motorcycle types".
There is no description of shoes or belts etc, but Paula is described as wearing a short-sleeved white blouse and faded blue jeans.
Also, in the November article it says that she is/was being considered as a possible for a Jane Doe found in a communal grave presumably at some point contemporaneous to November 1972, which was being investigated by Mendocino County Sheriff. Anyone know what case this might be? I cannot find any article about Paula after November 1972, except that in May 1980 her husband was granted a divorce from her in absentia (so presumably she did not turn out to be that Jane Doe).
Won't do any more digging in this thread as it's about the Jane Doe, but just from looking there doesn't seem to be anything that completely doesn't fit, or isn't explainable.