yitayningwut,
Maybe that Gemara,in Kesubos, means that the hair of the head must be covered, as the Gemara in B’rachot (24a) says that the hair is the Ervah. If you are telling me that the head is the Ervah, then I could say that wearing a burka would be obligatory to cover the whole head. Clearly, covering the head (as mentioned in in Kesubos) means to cover the hair OR the hair & scalp. I think that it means to cover the hair.