If one were to make a one piece (split back) head mold of out body double (or any other silicon rubber), could you make latex masks in that mold in the same way you would do in a plaster mold?
Not really , you need to have the mold pouress to absort the water from the liquid leaving the rubber skinning the mold, you wont get that with a silicone mold
Lots of thin coats with a fan blowing into the mold would do it. Letting each coat dry thoroughly before adding another. Will take forever but technically possible.