It's difficult, but try to separate what happened to Camden from the equation. Is there the possibility that all the secrecy and the lies were because JM didn't want her family/friends to know she planned to drive 1800 just to see a friend, like she did last Fall? (that's in an article a few posts back and I can't seem to 'quote' from this stupid phone)
Doing that, with a small child, may have caused family/friends to come down on her, so perhaps she lied because they wouldn't approve. If you subtract what happened to Camden, and imagine that in the end she and Camden would have gone home, then the way she lied and covered, no one would have been the wiser. Camden would have gone back to school and life would have gone on.
So just maybe, she DIDN'T 'go to' Maine. It seems more likely that the area around Stone Gable Inn would be where she was headed all along. When you go on a trip, you find a hotel close to the area of interest to you, right? Maybe she went to see a so-called friend, just as she is reported to have done last Fall....what, eight months ago? I'm still betting on an internet connection between JM and SOMEONE close to the area of the hotel.
I've got this thing rolling around in my head and I just wonder if all the secrecy and lies, prior to May 13th, was simply because JM knew her family/friends found her to be impulsive, and she didn't want to hear it?
There was screaming heard at the hotel, right? It seems to have been assumed that she was screaming at Camden but could she have been on the phone, angry that she'd come all that way, and that the person on the other end of the phone ditched her? Or, could there have been someone else in that hotel room, someone who knew the Dennett Road area of South Berwick?
Unlikely, sure. I know I read too many Stephen King books, but I just get the feeling this whole thing isn't as cut and dry as "impulsively planning" to drive 1800 miles to kill your child.
For someone who, we guess, doesn't know South Berwick; how on earth does JM leave the Stone Gable Inn early on May 14th and wind up on a deserted area of Dennett Road at 7:30 am....a mere two hours after Camdens reported TOD?
ETA...and remember, according to Mr. Lyons, JM told him on May 13th that she only had $25. Not a lot of money to drive around aimlessely, looking for a dump spot.