Plastic buckets are MUCH more oxygen permeable than lambic barrels, or homebrew-sized barrels for that matter. Using something like a Better Bottle or a carboy with a wooden stopper would be your best bets.
If you have any acetobacter in your beer, it will scavenge the oxygen and produce acetic acid. Desirable to a limited extent in the Flemish Beers, but not in lambics.
The Fiesty(sic) Goat Brewery est. 2007 & Clusterfuggle Experimental Ales est. 2009
Planned: sLambic II, Flanders Red II
Primary: Fat Man Porter, Orange Blossom Mead, sLambic I
Secondary: Flanders Red I
Kegged: 3 different ciders, Janet's Brown, Barrel-aged Stout, Hallertau Blanc Pale Ale
Bottled: Flanders Red I