Broken record...
From things Rose said, like BL taking GP’s ID so she couldn’t leave, plus the altercation in Moab where he seemingly took her phone and keys, to his five day trip home from 8/17 through the 8/23, leaving GP in a hotel, it appears BL might have a pattern of isolating her. Add to that the unverified reports of seeing him alone acting weird in the van on 8/26 and drinking alone in West Yellowstone that night, it might be that he left her alone at the campsite regularly. It's why I don't think those unverified sources are unrealistic.
The bigger picture, imo, still leads me to think it is possible that after the Merry Piglets incident, he was angry and he left her alone at Spread Creek campground, with the van, but without the keys or her phone, while he went hiking for two days. This would be typical isolating behavior for him, imo.
If he knew he’d left GP stranded without her phone and alone in the campground, the last thing he would want is for the lady who he hitchhiked with back to the campground to then drive him to the van and have GP tell her what he had done. So, he insists on getting out at the entrance.
His text to GP’s mom on 8/27, about Stan, maybe wasn’t even him making a mistake and wanting her mom to think it was her. Maybe it was BL asking for Stan to stop calling (or whatever) because he had her phone on him and was sick of it. By the 30th, she was dead and he wanted no contact, so he wrote the Yosemite text, which basically was saying there would be no more phone reception, so no more contact. IDK.
The general consensus seems to be that he left for his hike after killing her (for an alibi, maybe), but I still can’t grasp him taking off, leaving her body near the van for easy identification if she were to be found, all while he’s still in the park boundaries and on foot. It just doesn’t make sense for him to do that, then hitchhike back to the crime scene. I can’t get past this.