It's worth having at look at the Northwave range. I've size 48 flippers, wide ones at that nd have bought two pairs of theirs as they're such a comfortable.
One other thing I’ve heard, and I don't know if it's true, but those of Northern European origins, i.e. Anglo Saxon, Viking, Scandinavian, Germanic typically have wider feet than those of Mediterranean origin. Whether that explains why some Italian manufactures produce predominately narrow shoes I don’t know, but what I do know is my flippers are never going to fit inside any pair of pointy Italian snakeskin shoes, real or otherwise.