What is the localized geology like? Any Limestone terrain around? If so, look for burnt rock middens/ hearths. If no limestone and coastal geology, look along the top edges of the banks for any lithic scatters, and do small periodic test holes while taking note of any surface stratum changes. Sometimes the confluence of a creek to a river is a good spot to check, and places along banks that have protection from a North wind. About all I know to suggest without more info.
I myself have been trying to pinpoint the camp at my place. Behind the area of all the arrowheads, is a revene(sp).. pretty deep, I've scratched around there with no luck. I might give it another try. The ground is basically sand, and rock.. tons of flit, red's, yellow's, white rocks.. all styles...etc.. its a rock heaven for a geologist if you ask me~.. What other info is needed to locate the exact spot?
I have another location in Lampasas County that is along the top of a very tall ridgeline (probably 350-400 ft. in elevation above grade). In one section on top there is an area that is covered in very large pieces of flint. About 100 yards from this there is a cave. The roof has definitely been burned in the cave. I went into it about 12 years ago but did not dig. The ground is limestone but the dirt inside the cave is very loose. The cave is about 10 X 10 X 5ft. high. At the back of the cave is a tunnel about 2ft in diameter that goes farther than my light would shine. I went back to the cave mouth before deer season this year to see if I could find it again and found an unbroken arrowhead that had obviously eroded from the cave mouth.