If you can find it, you might want to check out
Nightmare in Badham County (1976). It was a TV movie, but they filmed extra scenes of nudity for the European release and that's the version that occasionally gets aired on the pay channels. It's also supposed to be available on tape.
Deborah Raffin and Lynne Moody are driving cross country when they manage to p**s off the sheriff of a small southern town. Faster than you can say "corrupt legal system", the girls are railroaded into the county work farm. Of course since Raffin is white, Moody is black and this is the south in the 70s, they have to be separated and bunked with their "own kind". Sadistic guards, beatings, nudity (I don't recall any from the stars), scenes of lesbianism, escape attempts, the usual stuff. No humor at all, other than possibly some unintentional laughs at the dated setting and dialog, and kind of a downer ending.
I originally saw this on late night network TV at a young age, possibly my first WIP flick, then later on one of the pay channels, where I was surprised at the various scenes they added.