Looking for ways to make headless costumes.

I am planning to make 6-8 for a set next year. I do not want the kind where the actors head is showing. I want the actors head hidden and the neck showing.

I was thinking of putting expanding foam into a can to make the necks but not sure on the best way to attach it to some sort of structure to hold it upright.

I was also wondering what kind of fabric or other item to hide the actors eyes or face.

I will use these customes which would be covered with "normal street cloths"

Thanks for any help that can be given.