The reason the older stuff seems to be found further south is probably because of the meteor(s) disaster in upper North America around 13,000 years ago.
Sunken Civ can post reference to a book about this still largely unrecognized answer to such questions as, why were so many of the large fauna gone so quickly around that time. Also why did Clovis end so quikly, etc.
Monte Verde is in Chile, so when Tom Dillehay started reporting on the age of the stuff he was finding, there was a great deal of controversy, because it would have meant the Bering Strait Pedestrians would have had to have sprinted there to fit into the generally accepted time scale for humans in North and South America. I had read in an interview that he found stuff that he believed was much older, but he did not push it because of the struggle he had had just to get recognition for his initial findings.