There was a theory I read previously and totally agree with, basically stating Brian abandoned the van after GP’s murder and followed the river until being picked up on the 29th by youtuber. In the hopes that the van would be found, and his alibi would be he was hiking. In this occasion he followed the spread creek to the snake river. With this being said, I feel he is most comfortable following a river or creek. I would be searching near creeks and rivers for him. Not lakes and swampland. I also figure he can maneuver at a pace of around 10-15 miles per day, so this gives a search radius of 70-105 miles. If he were to head south, he would most likely run into more civilization so Imo he would be traveling north. I think he is between Alafia River state park and Colt creek state park.