1812 is before Andrew Jackson, who successfully won a battle against the European Bankers. He was also the first President to have an assassination attempt on him. The guy's guns misfired, and Jackson started beating the crap out of him with his cane. 1812 is just a few decades after the founding of this country. Going back even earlier puts a whole new twist on all of this and precisely how old some of these KGC marks may be and what folks like Jesse James were doing - maybe not as much stashing and more relocating/recovering and spending going on during his time, following up on older reports/rumors/maps. Merely speculation on that last part, on line of many I can see if your research is ultimately correct. That would be yet one more game changer for how to approach and research all of this stuff, for 'KGC' research could really start pre-1776, in the traditional KGC sense.
I think expeditions out to the west, namely the folks who ran them, like Pike, Frémont, et al, are people to look into and question their activities. I haven't made the dive into them completely, but I think a lot of those reports from those early expeditions to be important things to study carefully and see if there are things to be read between the lines.
Pike led a couple of exploration expeditions for General James Wilkinson. Wilkinson not only conspired with Aaron Burr to seize land west of the Mississippi and northern Mexico, he was also a Spanish spy. Wilkinson sent Pike up the Mississippi to scout for fort sites and, during this expedition, Pike stopped at the Dubuque lead mines in what is now Iowa. Pike questioned Dubuque about the output of his mines but Dubuque became suspicious and gave him false numbers on the low side. It could be that Wilkinson was looking for a source of lead to be used for ammunition. Some historians believe Wilkinson might have been responsible for the murder of Meriwether Lewis, even though his death was ruled a suicide.
Here's a story about Burr that seems kind of odd.
The Eye of Theodosia Burr | New York Rediscovered
There is a mountain in Colorado named Emma Burr and it seems nobody knows the origin of the name.