Here is another thought, maybe CB was not the planned dumpsite? There are many lakes above CB as well as lakes surrounding Quincy. Maybe she was taken to a different site and the murder had to back track and decided to dump her at CB.
If I remember correctly, there was a body or two dumped at Quincy lakes several years ago. Also, I cannot remember the name of the lake; however, on the way to Quincy there is a large lake on the left. While I cannot remember the details, a heard a body was discovered in that lake over 20 years ago and to the best of my knowledge the case remains unsolved. I also know of a place, where I fished as a child that is by the junkyard near Quincy. A couple of years ago I went there, scouting for a good fishing spot. It is now very run down and eerie. I reminded me of a place where Ted Bundy may have dropped off a body. There were also some individuals of a questionable nature hanging out around the lake. Not a family fishing trip, I left and have not been back.
If she was alive and subdued, maybe she was taken to a more secluded area near Quincy in Grant County. That would mean the murder took place in another jurisdiction.
The place near the junkyard is secluded and away from civilization; anything could be done, anytime of day, without attracting attention.