i know exactly what you mean when you say your thoughts are a bit too scattered to put in a reader friendly format- it took me forever to post on here because i didn't know a good way to organize all my thoughts on her disappearance lol...while i do support the suicide theory based on the evidence put forward, i definitely do consider other theories possible, and that's what has me fascinated w. this case. IMO, the theory you believe is largely dependent on how much weight you put on certain pieces of evidence, and w. so much of it being circumstantial, anything could theoretically be possible. as for my own experience, i can't imagine what my family would have thought if they had found just my car in some rural area in western WI. I suppose they would have eventually put two and two together and realized I was on my way to minneapolis, but there would be no reason to initially assume that based off the route i took. that's what makes solving MM's case so difficult- we have no idea why she was where she was, or even where she was headed. also, like you stated earlier, if she was abducted, she could theoretically be anywhere (although statistics show she'd likely still be somewhere in the area). also, another thing i often hear used against the suicide theory is that she would have been unable to hide her body and she would have been found by now. i very much disagree w. this assumption- supposing she did take off into the woods or down the road to either hide from police/end her life/walk somewhere to find help, she could have survived for awhile if she kept moving, since temperatures weren't much below freezing. she was a long distance runner, who knows how far she got (or even what direction she went in) there have been people missing in rural areas that have taken 15, 20 years to find...and it turns out they were near the original search area in the first place. i think a lot of people wrongly believe that if the search area is known, finding the body is easy, when there are a variety of factors that can very much complicate it...compare that to MM's case- we don't know what her intentions were, so finding her becomes even more difficult.
My reason for not supporting the runaway theory doesn't necessarily hinge on the sentimental items so much, but that i don't believe the evidence put forward has shown anything so horrible in MM's life that would warrant running away and never being heard from again. I don't see credit card fraud as a reason to runaway- the charges were going to be dismissed. if she did in fact runaway, there had to have been something SERIOUS going on in her family or personal life that the public didn't know about. people don't start new lives in Canada for minor credit card fraud.
As for the rag, I don't believe the tow truck driver was lying (you're exactly right in that he'd have no motivation to lie) FM, however, certainly COULD have a reason to lie (i don't believe, like Renner seems to imply, that it was for anything sinister) Renner interviewed the tow truck driver years after the fact...if Renner asked specifically about the rag in the tailpipe, it's very possible the tow truck driver had heard it reported at some point that FM had advised her to do that (because it's widely reported FM said that) and eventually just assumed it as fact. There's always a risk w. interviewing witnesses years later, because memories fade quickly...if Renner was asking leading questions (which I'm not implying he did) the witness is going to be more likely to tell him something along the lines of what he wants to hear...especially if they really don't have much info to give in the first place. Did the tow truck driver ever say prior to Renner's interview that he heard FM tell MM to put the rag in the tail pipe...if so, it would have a lot more credibility (IMO)
As for Renner, I don't think he's a liar, and I do believe he does want MM found, but I think that he is so attached to his theory that he looks for evidence that specifically supports it, even though his theory is so complicated and has so many holes it's nearly impossible to believe. So much of what he puts on his blog is just gossip that has nothing to do w. her actual disappearance. I also don't like his implications that FM is somehow guilty of something. I do believe FM is not being entirely truthful, but I think he's protecting his daughter's memory and trying to keep police and public searching for her.
One last thing about the rag...supposing FM did actually give that advice about the rag, it likely means her car was in pretty bad condition and should have never been driving to NH or VT (or wherever she was headed). That makes, IMO, her reasons for leaving extremely important. Most of the scenarios people have proposed- treatment clinics, abortion clinics, going away to collect her thoughts- could have all been done a lot closer to Amherst. If she was taking an unreliable car to NH w.o telling anyone, she had a very important reason to go to the area she was going. That's why I think people should really consider FM's initial reaction- he tells police she's gone to the white mountains to die, tells people about a story he told MM at some point about how he'd go off into the white mountains and drink himself to death, and then gets on TV and tells her to come back because "any problem we can work out, just like we always do". Then he does a complete 180 and starts insisting a local dirtbag took her and nothing else mattered prior to her disappearance...while giving no explanation of why she was in Haverhill, NH when she should have been in Amherst, especially after he told her to stuff a rag in her tail pipe because her car was in such bad condition. Going back to my experience one last time, had I ran out of gas or my car broke down in an area of western WI, the first thing my family would assume was that either my car had been stolen and I was still in Chicago, or that I had met with foul play or been abducted. I'm certain it would not have been suicide- there would be no reason for me to commit suicide off a dirt road near Eau Claire, because I had never been there and it held no significance to me. there was a reason that FM initially assumed suicide and made comments about dying in the White Mountains...i know that he was frantic and maybe saying anything that came to his mind, but even if that was the case, at the very least it showed how significant the White Mountain area was to her.
Obviously all of this is IMO, since none of us know what actually happened and so many pieces of the puzzle are missing.