my left foot is wider and longer than my right (probably from so much skateboarding/pushing when I was a grom). It's not as much as BA, but definitely noticeable.
I don't ride that much. I like comfort from the start, so I buy boots that fit my bigger foot good and snug and the other foot is slightly "loose". Just different lace tightening per boot works for me (barely), but if it were any worse, I'd fit the loose boot with j-bars, heel wedges and maybe even thicker socks...whatever it takes to fill that boot out.