Just a thought here that I don't think anyone else has mentioned. I doubt that the abductor thought he was seen. He most likely didn't know that Holly's brother was home. Remember, he did this after the parents left for work. Does that change the thoughts about why items might have been discarded in the way they were? I wonder if he left something at the school of significance thinking that she would most likely never be thought to have been abducted way out in the woods that she lives in. It would be more likely that she would be abducted perhaps at school. Her car would have been left there at her home, but people would be confused about that and wonder if she somehow got a ride to school for whatever reason and was abducted at the school. Would that possibly point to another abductor? I'm getting the picture that this guy had a plan to confuse LE in the first place by planting the clues. This would be good news in that (in this scenario) he abducted her and got her out of there by car as quickly as he could, got her to the place he is holding her (incapacitated of course) and went back either that day or even a couple of days after (I don't remember what day they found the lunch bag) and then began to leave "clues" that would lead LE in another direction.
If the purpose was something more sinister, he would have done it in the beginning and wouldn't really care if she was found because he thought he had kept any trace of his identity out of it.
There are other scenarios I'm sure could be thought of because he doesn't know that LE had a witness seeing him do the abduction.
Also, the guy listed above as a possible abductor who was stalking other girls, I think this actually could be another possibility. If the brother was able to make out camo and it being worn by a man, he would just logically relate it to the boyfriend because it is what Holly and him wore a lot when hunting. From a distance, and with no glasses on, he might have been able to make out the camo, but not the exact height and weight and guessed on that. After all, that guesstimate about the ht and wt of the abductor was pretty general.
Just a thought. Would love to hear all of yours.