I SMH at this logic. Shoe sizing is a matter of Height x Width x Length, not volume. If you had liquid feet, this might work, but since you don't, you will need to get the right dimensions, not just the right "volume".
Something that is 25 x 25 x 2 will not fit in a container that is 25 x 10 x 5, even though they have the same volume.
If they are just a "teeny [sic] bit" tight, there is hope, but anything more than a little snug and I'd say you are SOL.