Brilliant post mdog. People ought to print it and refer to it often. I have a couple comments.
First: just because you find a couple piles of rocks or a carving somewhere doesn't mean you're on the "treasure trail". These things are everywhere and have many innocent purposes. Some have even been created by pranksters in the past few decades. All you have to do is get yourself a nice cold chisel and a three-pound hammer, go find a big rock where people hike near, and carve an arrow, cross, turtle, etc. If the rock is the right kind, you can then use a fine rasp, some emory cloth, etc, and do a decent job of "weathering it". People will notice your creation, and eventually, someone will wonder if it's "Spanish". In time, a legend will be born. Heck, I saw something similar happen with a simple real estate transaction near Silver City several years ago - and there was no hoaxing involved. A guy was walking around and found a carved stone near an old fence line. He was sure it was a treasure map. It wasn't - it was a surveyor's corner from the 1800s. They used carved stones then, sometimes intricate. The guy found the property owner and bought the land where he figured the treasure was buried. Then he began digging dozens of holes all over the place for years. My surveying buddy told him he was wasting his time, but the guy couldn't believe it. He's probably still digging if he hasn't died trying.
Second: Re more "legitimate" treasure signs. I've seen a lot of obviously well-engineered patterns of clues that accompany "treasure legends" (well-known and not so well-known). You've showed me some amazing large-scale map patterns that boggle the imagination. We want to assume that this stuff was created to hide big time treasure caches, and maybe they were. Or not. I was told by a very smart guy some years ago that these "KGC layouts" may be simply a learning opportunity for curious folks and that there may be no pots of gold at the ends of the rainbows - only the knowledge gained on the journey. When you think about it, a guy has to keep educating himself in order to keep chasing down these things. Or, maybe the whole thing is some sort of initiation exercise for some group of folks. Whatever it is, you find yourself studying up on all sorts of things - history, genealogy, ancient cultures, geometry, cartography, symbology, philosophy and more. That can't be bad for you, and like you said - you don't really need to find gold bars. It's still a thrill to find just a little old arrowhead.