The uncertainty was real. Plus the Mexican force in Arizona, a small force of cavalry stationed at Tucson, immediately retreated south on the approach of the Americans, without a fight. Remember Santa Ana capitulated in 1847, Arizona was entirely under US control in that year.
Josiah Gregg, who was with the American army in northern Mexico, said that "the whole country from New Mexico to the borders of Durango is almost entirely depopulated. The haciendas and ranchos have been mostly abandoned, and the people chiefly confined to the towns and cities."
The Mormon Battalion marched across Arizona. It would have been almost impossible for a party of miners to NOT hear of the war and how it was faring badly for Mexico, by the 'panic' that spread ahead of the advancing American forces.
I would also point out that while 1847 is logical to see as a date, not every number on the stones then must be a date as well. Why would anyone bother to mark more than the year of the claim? Your argument reminds me of the Atlantis discussion skeptics. Alan explain why 1847 should
not be viewed as a date please. Thanks in advance.