I'm a 13 EEE...really a 4EE but rare to be able to find those.
My son wears a 16 and as wide as you got, his foot sticks off the side of a standard brannock device.
Regarding Carhartt boots. I hate them. Bought apair and took them back after a couple days. The place was awesome about allowing me to return.
For a mass produced work boot these are hard to beat:
Two Harbors | Irish Setter
I prefer a 1178 or 1155 red wing slip on...made in usa, hand stitched goodyear welted...They run about 220 but can be resoled (by redwing) for $50 and so long as you dont light them on fire your kids can wear them.