Do women need to be separated completely from men during prayers?
No. There is no need to separate women from men while praying. However, Allah describes the believers as “who humble themselves in their prayers” (23:2). So, in order to establish a proper atmosphere that will help us be humble in our prayers, it would be wise to let men be in the front and women in the back. Reports from the Messenger of Allah show that he arranged the people in mosque like this (see: Bukhari, Prayers 20, Call 78, 161, 164; Muslim, Mosques 266-268, (658-660); Muwatta, Shortening the Prayers 31; Abu Dawud, Prayers 71; Tirmidhi, Prayers 173; Nasai, Mosques 43).
Therefore, it will be enough to just let women stand for the prayers right after the last line of men. There is no need to send them further away or put some curtains in between.