Why not make charcoal near the burn piles using a slight depression in the ground, or some barrels or other tin. When I constantly add wood to my 55 gal drum after the bottom vent holes are covered, it acts as a flame cap kiln, and I end up with over 2/3rds of a barrel of charcoal. It takes about 25 gallons of water to extinguish. After I added water to the last barrel I made a few days ago, the water was right up to the rim of the barrel, but the next morning the water was all gone. There were only a couple of brands from some ten inch diameter hunks added toward the end of the burn. You would just have to haul water to the burn site, spend about 3 hours in the early morning feeding the fire, and then extinguishing the coals. Invite a friend to help. With help, you could run two barrels at once, sitting a few inches apart. (Need room to cover the vents with dirt when those holes start glowing.) I recently ran two barrels at once, but my 75+ year old bones got wore out.