Fascinating theory...This American Heritage article tackled the question of John Smith's tales of his service against the Turks. http://www.americanheritage.com/articles/magazine/ah/1958/6/1958_6_28.shtml He was not a liar, as the research shows... "There were also, at the time of the English landing in what is now Virginia, well over 20,000 persons of European descent already living in what is now Maryland." I would find this very hard to believe... There were pockets of French and English, usually survivors of shipwrecks, often living in harmony with the Indians. John Smith's journals give us a very true account of Virginia and New England. I reckon the old adventurer would have shared a word or two about his Croatian adversaries were this the case!
Let's imagine John Smith, chosen for his facility in Turkish, dealing with Turkish speaking Europeans ~ Christians in fact ~ the Spanish did not kill their Orthodox prisoners.
Probably struck him as quite normal and unremarkable.
Going beyond the French and English, there' been Welsh, Scottish, Breton and Scandinavian fishermen drying catches in America for the last 75 years (as the Grand Banks, et al, slowly recovered fish-stocks after the harp seals had been killed off).
Chesapeak Bay was a great place to be during hurricane season, so you'd had all sorts of people wintering over. As long as they gave Powhattan and a couple of other Iriquois tax collectors their share, they could do what they wished.