While it’s possible – that is, within the range of human skills – that the Vikings traveled 1000 miles inland in one trip, note that their explorations tended to be in short bursts, establishing colonies and trading back and forth. Ireland, Iceland, Greenland, Newfoundland, in sequence. This pattern would suggest settlements and exploration much more gradually on the way to Minnesota, over hundreds of years, leaving evidence along the way.
Yet we have found nothing to suggest that actually happened.
And all the known exploration was along the ocean and the Atlantic coast. All of the settlements were on the shore. Minnesota would have been an unusual inland turn for cultures wedded to the sea as much as they were. Finding artifacts in New York on the lower Hudson would be much more logical than 1000 miles inland, far from any major body of water, even if you include the Great Lakes.
As far as the stone’s inscription being “simple” and “readable”, remember that it was chiseled in stone, not written with a quill pen. That would encourage brevity and discourage floridity. I don’t think you can directly compare it with 14c books and expect a perfect match for this and many other reasons.