In this case, secondary and aging are basically the same thing. Be sure to taste frequently while it's in the barrel, you can't "undo" oak. CO2 purging might work but you should do it every couple days because that barrel is not air tight. You could also top up with a similar commercial beer. The smaller the barrel, the faster it will impart flavor (volume to surface ratio).
Something is always fermenting....
"It's Bahl Hornin'"
Kegged: Bourbon Barrel Imperial Stout
On Deck: German Lager