I think the best place to look, on whether he arrived at the campsite or not, would be at the most recently released professional theories of LE and KI. There has been some doubt expressed about whether he was on the Friday trip to town, based on the absence of definite sightings at shop and pump, but that doesn't rule out arrival at campground on Thursday MOO.
I find it hard to believe that LE/KI would base their professional theories solely on the absence of independent sightings of Deorr at the shop or gas station.
Four people on the trip have said he was there.
The tracker dogs first on the scene trailed to the reservoir.
There were clothing & personal effects pertaining to Deorr at the site.
The consistency in all 4 statements is that he was present at the commencement of the trip to the fishing hole in the afternoon. Whatever happened, it occurred after that point in time IMO.
If LE/KI had solid evidence placing the lad elsewhere at the time the journey to Timber Creek first started on the Thursday I think we would have heard about it by now.