Doing 2.5gl batches in 5gl buckets is the only way I brew for now. However, when I bulk age or secondary, I move it to a vessel with less headspace.
Drinking Fat Tire Clone
Carbing/Aging Westy 12(new world), Chocolate stout V2, Pumpkin Ale V2.5 (1st batch 2014)
In the bucket Pumpkin Ale V2.5 (2nd batch 2014), Kinda Double Bastard
On Deck The Kaiser, Blue Moon, oatmeal porter