I think that you should check out the USCCB Mandatum, as it seems to contradict the fact that those to have their feet washed must be men.
“While this variation may differ from the rubric of the Sacramentary which mentions only men (“viri selecti”), it may nevertheless be said that the intention to emphasize service along with charity in the celebration of the rite is an understandable way of accentuating the evangelical command of the Lord, “who came to serve and not to be served,” that all members of the Church must serve one another in love.”
My reading of this text seems to allow for both genders to be represented in the feet washing ritual.