I don't doubt that you and others have more knowledge of the case as I've only recently stumbled upon it, but it doesn't seem like there is enough information here to lead one to be so certain about what happened one way or the other. Based on the information available, and what you've presented, I still don't see how you come to the conclusion that this was most likely a suicide.
First of all, regarding the temperature, I see where I made my error there. You're right, it appears the overnight low the morning after she went missing was in the 30's. I'm not sure if that difference in temperature means much, although 30 does seem comparatively warm.
Regarding the Westman account of a man smoking a cigarette in the passenger seat while there was a flurry of activity by the trunk. I don't see how anyone can backtrack and rationalize what they saw was a cell phone light inside the vehicle while there was a flurry of activity by the trunk. Does this mean there was no flurry of activity by the trunk? How does her husband seeing something different outweigh her original belief that there were two separate people in and around her car? It seems like you are assuming a lot of things that we can't prove/don't know as fact, such as claiming that she was coached into hallucinating what she saw by the 911 dispatcher, that doesn't make any sense to me. It seems like a stretch for you to assume who had a better vantage point, or assume that she was coached into believing she saw two separate figures, one inside the car, and one behind the car. Also, none of the witnesses seemed all that confident that she was even the one driving the car that night. The bus driver originally said he didn't think she was the girl he saw, he later changed his mind and said it must have been her. Considering that, can we really put that much stock in anything the witnesses said?
Regarding Maura's researching different locations, instead of using the words "places to live", I should have said, "places to stay". However, I'd like you to explain something to me. If the plan was to commit suicide in the White Mountains, why research places in Stowe Vermont and Burlington Vermont? Both of those locations are at least an hour and a half away by car. Why not find lodging closer to your intended suicide destination? That doesn't make much sense to me.
Regarding the book, I've read the synopsis, and I've read various summaries of the book. I think it's also a bit of a stretch to assume this book is related to her disappearance. If the book was truly the inspiration for her disappearance, why leave it in the car instead of taking it with her to read in her final moments?
I don't blame you for coming to the conclusion that this was a suicide, however I think the facts that we know for certain could point to a number of different scenarios. It seems to me that you're trying to massage the evidence to fit your suicide hypothesis. There is no hard evidence as to what actually happened one way or another. I don't think we'll really know unless someone finds a body, or in the unlikely event that she turns up alive somewhere. I'm not trying to be disrespectful or start an argument, but I feel the notion that this was a clear cut suicide must be challenged. If it was a suicide, no harm done. But if there actually was a crime here, and we write it off as a suicide, we'd be doing a grave injustice.