Frankly, going to "abduction" seems strange to me. Getting picked up by concerned strangers...much more likely. My parents never picked people up when they traveled, except in the desert. Single women, children, they picked them up. They then taught me never to do that. But people still do it. If Barb was upset and by the RV, and if RT's estimate of how long she was there is off...I could see that happening.
Could it turn into something more sinister? Sure. But a traditional abduction might not have taken place, it's possible she was offered a ride in an air conditioned car and went for it. She would surely have contacted other family members by now, though.
A whole lot of forensic questions I'd ask, if I could, such as Barb's relationship with alcohol, whether she was known to go on benders, etc. Since it seems she wasn't into SM and did not usually have a cell phone or go on the internet, she might not even know that a huge search had been conducted. Surely she would have reached out to her brother (if she had his number memorized). Did she? I'd want to ask RT what numbers she knew by heart.