A 2 box set up is definitely a specialty tool for out of the ordinary treasure hunting. What is needed to go along with the tool is knowledge & technique. Bottle dumps, large Civil War relic & hut sites, substantiated Caches and Post Hole Banks are not common features of most Permissions but they exist. Research and lots of time on the ground is required. You also have to work smarter not just harder. A proper set of ground/bottle probes can save you a lot of unproductive digging as will a big coil on a good VLF discriminator. It is tough to do alone but that is what a lot of the early guys did with less equipment but more time and more opportunities. Can you imagine being able to hunt along the actual Oregon Trail before it was all obliterated or fenced off? There were scores of Pioneer trails thru hostile territory. Or a battlefield or Winter camp? How about Galveston or Padre Island.
We have less opportunity today but better equipment. You have to admire those early hunters who were very secretive and successful.