You may want to think about replacing the three piece airlocks with S-type airlocks. The S-type airlocks do not suffer from the quick evaporation like three piece airlocks...
GREAT tip! I'll be steadily replacing my 3-piece airlocks - it really is a lot of upkeep to keep them full (especially for beers you want to forget about for 6-18 months).
...Each carboy is capped with a drilled natural cork and a 3-piece airlock. I'm using the natural cork to try to emulate the slight amount of oxygen permeation that occurs in large wooden casks...
Never really understood the cork stopper method. If anything, it only allows oxygen into the headspace, which is normally protected by a pellicle. That is, until you jab it with a wine thief, which I wouldn't consider micro-oxygenation parallel to pickup via barrel staves. Seems like the cork would just dry out, potentially absorbing moisture from the air and harboring mold.
Nothing but a barrel will give you just the right amount of micro-oxygenation. Buckets are a passable second.
...That little bit of oxygen is needed if you want the acetobacter to develop some vinegar character...
Micro-oxygenation obtained by wild beer in oak barrels is coveted because it can allow brett to express a wider variety of flavor compounds.
If you're developing acetic acid (above the levels of a good gueuze), you're picking up too much oxygen. Ironically, this amount of oxygen pickup will inhibit pediococcus, which produces acidity that is softer, more complex, and generally preferred over acetic.
If you really feel that your beer is lacking acetic character, try dosing (in the glass at first) with a touch of good balsamic vinegar. Of all the wild sours I've brewed or tasted, none
would have improved with higher amounts of acetic acid. But who knows.
*steps off soap box*