I have been skimming this thread, so I apologize profusely if I’m way off or if someone has already theorized this, but here’s what it looks like to me. Just my thoughts:
Something happened to Jessica on New Year’s Eve at the hands of her boyfriend. Boyfriend confides in Phone Guy and takes her phone to him early New Year’s Day so that he can hide her body somewhere other than the river (so the phone doesn’t ping with her body.) Phone Guy leaves the phone at his place but goes with the boyfriend to launch the boat. They put her purse and stuff in the boat to establish she was there (yeah, I’d never carry my purse in a boat.) Phone Guy rides down the river with boyfriend and at some point one of them gets out of the boat wearing the boots that had to be cut to fit. He’s wearing these to make it look like she got out of the boat. At some point he leaves the boots and coat behind to establish she was there.
A similar scenario is that something happened to Jessica at the hands of both the boyfriend and Phone Guy on New Year’s Eve. That would give Phone Guy more reason to be involved in a coverup.
It all sounds like a plan concocted by a couple of high dudes who watch crime tv. I hope Jessica is found and justice is served.
I hope she will be found so that justice can be served and I suspect that when all comes to light, there is a good chance that you have nailed this.