more basic medieval sewing questions

I'm making a stack of lightweight linen undertunics for Pennsic, courtesy of the Elizabethan Smock Generator. The smock generator suggests that you use a facing for the neck hole, but I have a vague sense that this isn't a very medieval solution, due to the waste of fabric; I'm tempted to substitute a strip of linen. Will this be more trouble than it's worth? How do you deal with neck holes?