This question has been asked numerous times before. My response:
How much do you value your face and teeth?
If the answer is very low, go without face pro
If the answer is medium or high go with some form of face protection.
keffiyeh AFAIK are soft clothing, it's not going to absorb any energy.
Having your mouth close is probably not going to works too well (if it hits you >1J impact velocity) your skin and transfer energy.
Lower face mask is probably the best. The lower steel face mask puts your face about 1/3" higher. So if you are running those 1/3 co witness, you are good to go. If you are running ACOG, put the ACOG on carry handle.