Otto- I am one of the ones that thinks Klunder is the likely perp here for just the reasons you stated. I find it difficult to get past those odds. I also believe that there are likely other crimes committed by Klunder that haven't been linked to him.
I agree mostly with what you posted, but I think 7 Bridges was just a dump site. I think we are missing the actual scene of the crime. As Klunder evolved, there became three sites, actually four. . .the abduction site, the place of the actual crime, and a dump site. The fourth in the KS case, is that he dumped their backpacks at a fourth site. Klunder was a big guy, 6'4" I think I read. Is that right? He also worked with hogs. I think he could have carried the girls in to where they were found.
IMHO, that fits here. Much of what we learned from his final crime are things we discussed here in this case before that even happened. . .the fact that the girls may have been lured to the lake, that a weapon may have been used, that the girls may have been zip tied, and whether or not the bikes were staged.
What else we know about Klunder is that he was not patient. His crimes happened soon after the abduction. KS was already killed by the time he was driving down the road looking for D and she was still in the woods. I think it's likely both Lyric and Lizzie were already gone and at 7 Bridges by the time their bikes were found.
IMHO they need to search every hog facility between Evansdale and 7 Bridges. Even if they do, I'm not sure how they would identify it as a crime scene. Aren't hogs actually killed in some of these places? How would you be able to tell if it was just normal pig blood or a crime scene? Ugh!
Anyway, all MOO!