There is folklore around Mulberry, AR of another Viking hieroglyphic site. Only locals are aware of it and it hasn’t been looked at professionally to my knowledge. What I wonder about that, making the assumption these are in fact of Viking origin, is how did they get this far inland? The Arkansas River was not navigable until we dredged it for barge traffic, unless Viking boats were wide based with little to no keel. We are talking about 600 miles inland from the Gulf. My understannding is that the hieroglyphics are inconsistent with Native American writings.
Viking longships are, in fact, wide, with not much in the way of a keel. From what I know of them, it is “possible.”
The runes are, as far as I know, as you say, incompatible with native writing. Dr. Savage’s conclusion was, he says, drawn from the fact that in excavations around the Heavener area, there are absolutely no viking artifacts. Not so much as a bead. Not sure how you would tell an Indian bead from a viking bead, but every other site I know of where the vikings stayed for even a little while, they left a lot of artifacts behind.
Best guess is 18th or 19th century hoax.