We don't know what makes those isolated farm locations of interest. Maybe phone or fitbit pings, or maybe something found there, ie. misplaced tire tracks, or disturbed area in the weeds/dirt. Or, maybe as lucky as a dropped receipt from the truckstop with a date/time stamp (maybe around 5pm, thus LE's timeframe). Or even another item marked from there. We just don't know those specifics.
Also, I think a local would go to a familiar abandoned building and low traveled roads, which explains why he might have headed into that southeren region.