I think there are "holes" in every theory I can concoct, but honestly, SA being guilty makes the least sense to me.
SA lived on that property in close proximity to his brother, sister, niece(s), nephews, and parents, along with customers roaming nearby at times he can not predict. His mom stopped over shortly after, and he went for dinner there as he often did, which shows there is somewhat of a built in accountability living there. That doesn't mean he couldn't have risked anyone seeing him or walking right up to his house while he was killing TH, but to me, it seems unlikely. On top of so much more that makes no sense about SA being the murderer; the bones being moved to right behind his place, the car very clearly left on his property, no dna of TH in the garage or trailer, Kratz's narrative at trial with no evidence to back it up, and more!
RH seems like a really likely suspect, his history with TH, his odd demeanor during searches and trial, the password issue, the cuts on his hands, and not even being able to say morning, noon, or night when he last saw TH. For this to fit, I think LE had to have been a lot more involved in the coverup, because I don't know that RH would have planted items on SA's property easily (the car I can see being planted by him but it's hard for me to fit the pieces of how and when he burned her body and planted it).
As for ST, I think he's top on my list. He lived on Highway 147 at the time, and TH most likely would have taken this route to get home. From what I understand, ST first mentions the bonfire, and also tells LE that he believes SA and BD had a sexual relationship (I'm not sure if he said inappropriate or he felt BD was ok with it?), and these both point to framing SA. I don't find it too hard to believe that when enough people, LE included, mention a bonfire that night, SA and BD, and even Barb, can think their timeline is off and maybe there was a fire that night and not a week prior, or whenever. (That sentence is jambled, I apologize, I can't find another way to word it.) I think it's possible ST murdered TH, burned her body, planted the bones and RAV4. He likely knew she was going to be there that day, and could have waited for her along highway 147, or right outside the Avery property. Did Bobby see something he shouldn't have and ST threatened him to help or just to give him an alibi!? Maybe. If he'd murdered her at his trailer and/or burned her on his property, he's had an unlimited amount of time to get rid of evidence because he was never looked at as a suspect, and his property was never searched.
