Hey ROP,
This sort of seems like a waste of time. Improve your odds, learn where the ghost towns are in your area. Then use Google Earth to view them, but wander away from them. One of my hunting buddies has a theory that results in finds. If you are off the beaten path you will find stuff lost by people in the old days looking for privacy. Use the library and read articles from the 1880's through depression era. If you stumble across a merchant, they may have buried coins. Check out the Saddle Ridge Hoard, great story, but spitballin with my digging buddies convinced me the story is highly dubious. They may have done their research, found an opportunity and excavated it. Not saying, just sayin. Ignore the treasure magazine and book stories about stagecoach, bank, and train robberies. 99% are b@*"$**t. "The robbers got away with the loot, the posse caught up with them a few hours later and killed them in a shootout, but the robbers had buried the loot." LOL...gold and silver coins are heavy and slow down the horses. The posse caught up with the bad guys, killed them, and divided up the loot. Hopefully this saves you many hours. Again use your Google Earth, you will find old foundations, old trails etc.
Good Luck!
Jeff