Las Lunas is ON the Santa Fe Trail. Last reference I made to that was in the context of Arrow Rock Missouri where we find the intersection of what appears to be a surveyed Spanish baseline extending from Washington DC to Arrow Rock (prior to the subdivision of the continent among several contending European states ~ UK, France, Spain ~ circa 1604) and a Meridian that extends all the way into Canada up to about 54 degrees north (the boundary agreed to in the West between Russia and Spain) (At Kensington Stone it changes from geographic North to Magnetic North neatly avoiding overlapping Spanish and French claims).
The Santa Fe Trail begins right there at Daniel Boone's land grant.
The American history along that trail begins in 1821 and by about 1900 folks were commemorating it by placing marker stones of some kind along its course. The Trail mostly followed the courses of the few rivers in the region due to the absence of water anywhere else.
Given that Santa Fe had been thought of as a Spanish/Mexican border town prior to the Mexican Cession, there's really no reason for the Santa Fe Trail to have not existed until that time. It's probably a lot older than we imagine. I suspect it could have been the route followed by the Spanish Surveyors in the 1600s as they sought to get a grasp of where the land north of Mexico really lie.
There's no way they could have done straight line surveying in that region ~ just too many mountains and too desolate ~ but the rivers are permanent features and probably showed up on Spanish maps in the 1600s. They could have laid down markers of some kind ~ I'd look for the letters AVM somewhere on that stone to see if it was authentic (circa 1600s) or later (circa 1900s).