My first reaction was you're overly concerned. A face pic isn't proof, people could think they might recognize an SP in person, but there's usually at least a little plausible deniability.
And if an SP shows her face, that's a huge plus for me. You can read reviews but everyone has their own tastes and the face is pretty important.
But after reading about how some SPs get screwed at the border due to their online presence, it doesn't seem that out of line if you want to give some girls a heads up about that.
As a middle ground between showing the face and blurring/cropping it out, how about some masks like these from my thread on
Favourite Outfits (and Recommendations for SPs).