Lots of good info here.. Re: Dakota fire pit... awesome idea on the prairies or flats, but a terrible way to start a large burn in the boreal forest. Just as a buried fire will stay lit for hours, a pit fire can easily ignite adjacent root structures if one is not careful. Ensuring adequate ventilation is key to reducing smoke. The more oxygen a fire has, the more completely or efficiently it can burn, leaving less unburned carbon to rise as smoke. Concealing the evidence of a fire afterwards... cutting a large circle of turf or top soil and setting it aside will provide a great place to start your fire (or dig a Dakota hole,) and the evidence of the fire can be concealed by replacing the turf when finished. This technique has been popular with nomadic cultures for centuries.