The FBI poster still asks for witnesses at Spread Creek from Aug. 27th through Aug. 30th. IMO, that indicates they have reason to believe BL was still at Spread Creek at some point on the 30th (I can't accept the explanation that they just listed a broad timeframe).
If GP's missing person report has a last known date of Aug. 30th at 7 am, I agree that is probably the "Yosemite" text presumably sent by BL.
My question is from where did BL send that text? The FBI knows the location, I'm positive, but was it delivered the moment it was sent, or was it sent from an area with no reception (like Spread Creek) and delivered as soon as he drove into better service (which is probably as close as the highway that Spread Creek is off of)? Was he just leaving Spread Creek at 7 am, possibly?
Officially, 12:00 am would be August 30th, so the text could have been sent from up to 7 hours (or 6 if he crossed time zones?) down the road, although I would suspect the FBI thinks he was at Spread Creek later than midnight to have that date on their poster. Either way, no matter how I look at it, I cannot understand why BL would still be at Spread Creek on the 30th, at all.
If the hitchhiking stories are accurate, that puts him back to the van no later than 8pm on the 29th, I would imagine. If GP was already dead, why would he hang around for hours and hours?