There are no Herbert Hugheses showing in Lancashire in 1911 with 4 children. There is one, though, with three. He's in the West Derby district of Liverpool.
The youngest is 5 months old, so there is time to squeeze in another birth to fit in your timescale.
At least one of my relatives was pregnant when her husband moved to Canada - the child was given the middle name "Alberta", but sadly died before the family was reunited.
I've also found a John Herbert Hughes, who sailed on the SS Zeeland from Liverpool to Boston on April 11th 1911.
Hughes, John Herbert, 29, M[ale], S[ingle], grocery salesman?, [read} Yes, [write] Yes, British [nationality], English [race], [last address] England, Chester, [nearest relative] mother, Mrs. FA Hughes, 25 Beaconsfield St, Chester. [final destination] Man, Winnipeg
Still the problem of marital status, which again seems to be confirmed by the census.