IMO Frazee has done a lot of work to muddy the facts,including making sure Kelsey's trail was headed to Idaho. He told people they had broken up, he told different times of the breakup, but he told people after she disappeared that they had broken up. He made sure he was seen with the baby, at work, to look like a devoted dad imo. Meanwhile we know now that he was soliciting people to murder her and he must have been planning what to do with her body, how to hide her so she'd never be found. Given that the phone was sent to ID, it would make sense that he planned to dispose of her in a different direction. I tried to research to see what a killer typically does, how far is the usual distance he disposes of a body, but I can't find anything. I would guess it would be less than the 800 miles to Twin Falls ID and it must have been done fairly quickly.
So if he travelled to ID to dispose of the phone and if he disposed of her before he headed to ID, where in the general vicinity would he have disposed of her? Are there any abandoned mining shafts within an hours travel time?
I know some have postulated that he could easily dump her out of his car and down a ravine, so what roads would lend to that kind of terrain, with little traffic so he wouldn't be noticed?
He seems to be quite certain that her body won't be found, so he must have disposed it of somewhere that would be nearly impossible to get to. Again, all JMO.