Seeking baby coverall pattern with legs, buttons and maybe feet

Hi all!

My friend is having a baby and I want to make a baby coverall with a Where the Wild Things Are theme. I'm thinking of a pattern with long sleeves and legs and buttons up the front for easy diaper changes, and if it has feet all the better (though I can add booties separately if needed). My plan is to make the coverall look like Max's outfit with the claws for feet and big brown buttons, then add a hat that looks like his crown.

I haven't bought a pattern in a good while and I'm intimidated trying to sort what's AI and what's not. Does anyone have a good coverall pattern they'd recommend?