You discourage the use of "vos"? You're kidding, Im sure.
Vos has no plural? Neither does "tu". (Techincally "vos" has a plural; it's "vosotros", used in Spain. "Vos", as you may know, comes from old Spanish, and "vosotros" is "vos" plus "otros".)
That "locally modified" imperative dates back at...