When Cooper was seen floating near Saturn he was well beyond the ring system. Is it explained anywhere how far the station was from Saturn?
Cooper Station was in orbit of Saturn.
“Cooper Station,” the doctor said. “Currently orbiting Saturn.”
Given that humanity now has gravity-control technology and reactionless drives, there's really no good reason to assume that they were in any specific orbit other than just kinda mooching around nearby.
For the record, Cooper was found "near" Saturn. Beyond that we don't really get any specifics in the script or novel, but the fact that you can distinguish individual rings would suggest that he's something between 100K and 400K from the planet.
INT. OUTER SPACE - LATER
Cooper FLOATS, dead or unconscious, near Saturn. In the distance we see two Rangers approaching ...