I am still leaning towards some kind of ring from outside the area moving in for awhile, finding and grooming several possible targets, and then grabbing one when the opportunity presents itself.
It just doesn't sit well with me that a long term resident of the area (pedo or not) would suddenly come out of the woodwork, grab the girls, causing them to seemingly vanish into thin air, and then go back under his rock, completely undetected. Practice makes perfect, no?
I think the bikes were staged. Or if not staged, the girls were taken at the lake so they would disappear at the lake. I think whoever took the girls had a pretty good idea that LE would follow the evidence. And the evidence amounted to a great big arrow pointing at the lake. I think this was done to buy some time, even a little. Even if the girls didn't stay in the area long, I think the ring would have needed time to pack up and move out.
I think that while the FBI knows enough to believe the girls are alive, they don't know who took the girls or where they are now. I think the ring was in the area long enough to possibly get to know some locals, who might have unwittingly provided direct/indirect assistance in the abduction. Perhaps something as simple as, "hey Joe, let me borrow your van for a day," and, "you bet, let me get the keys."
I wish this case could be neatly cut down by Occam's Razor. But I don't think the simplest set of events can account for everything I know about this case.