I just don't really understand what is going on with the process.
Within the leaf cells, there are two principal oxydase enzymes that break down albuminous proteins and carbohydrates. The process is not microbial. It requires some moisture to be present, and temperatures above about 60ºF. The enzymatic reaction is temperature dependent, up to the temp at which the enzymes are denatured (~149ºF for the primary and more active oxidase, and ~191ºF for the secondary and less active oxidase).
A kiln uses artificial heat (and moisture) at temps between ~120 and 130ºF. The process is complete or nearly complete after 1 month in the kiln. Above ~120ºF mold will not grow.
The pile method (those are the pilones used in the Caribbean growing areas) utilize a huge mass of tobacco (5 or more feet high, and at least that wide) to provide thermal insulation for the exothermic (heat-generating) action of the oxidase enzymes to heat the inner parts of the pile. The pile is broken down and re-built periodically, so that all the tobacco spends adequate time in the "heated" core of the pile.
Simply aging the tobacco in a shed (for 1 to 3 years) would eventually allow the same enzymatic processes to occur,
so long as the temp is above ~60ºF (preferably higher), and there is adequate moisture, and the tobacco does not mold--which happens easily, when the average relative humidity remains above 70% for a few consecutive days.
So in sub-tropical and tropical areas, allowing tobacco to age under natural conditions is not usually practical. In temperate regions, it may be possible to age tobacco for prolonged periods in a ventilated shed.
For most home growers, the straightforward solution is to build a tobacco kiln ($50-$150), kiln tobacco for a month, then dry it down for storage.
Bob