You mention that the Heavener stone has Rune letters on it. So my questions are, why would a Spanish marker have runes on it and if they had 1600s Scandinavians doing surveying, were they still using runes by that time?
They didn't get out much ~ the 30 Years War hadn't yet happened, and the idea Sweden would be a major world player had not yet penetrated ~ they were still mostly illiterate except plenty of smart guys did learn and use Rune alphabets.
The big issue in dating all the Rune stones in the USA has been whether or not they were placed by Vikings in the early Middle Ages, or by Other Scandinavians in Modern Times.
My proposal here is they were placed by Late Medieval/Age of Exploration and Discovery Swedes employed by the Richest Man in the World ~ aka Philippe of Spain!
Being surveyors and navigators they'd been quite educated for their time, and it probably occurred to at least one of them that if he set benchmark stones in place with Rune or Hebraic Characters cut into them PEOPLE WOULD KNOW THEY WERE benchmarks and not just something else.
I think at the time most Scandinavians were totally unaware of the voyages to Vinland ~ Iceland was, after all, far away and very much outside the main avenues of world commerce. People weren't into digging through the Sagas ~ and translating them into English.
I think we actually know the surnames, and some of the Christian names of the Scandinavian surveyors who worked for Philippe in carving up North America!