Frankly I never accept at face value any claim that something has anything to do with Mormonism until i see Hugh Nibley's name on it. Having read a great deal of his material let me say this about that ~ he tends to be inconclusive on the darndest things!
Here's the only way to think about some mysterious rock in the middle of no where with misspelled Hebraic inscriptions ~
(1) That you are in Israel, Jordan or Syria., or (2) Why is there only one of these things around?
Every now and then somebody finds something stored in the Prado in Madrid. I'd look there ~ this was a piece of Spain for 300 years!
M, the Santa Fe Trail terminated in Santa Fe. I believe you are thinking of the Camino Real, which went from north of Santa Fe all the way to Mexico City. Los Lunas is on that road.