I don't know how common it is, but I suppose it can be done. But I think they'd vest in their rank, not in the rank in which they are functioning. So bishops may "serve" as priests do and not hierarchically, but they still use episcopal vestments, priests may perform diaconal functions at hierarchical Liturgies without deacons, but they are vested as priests, etc.
The Roman rite, and perhaps other Western rites, allowed you to serve in an inferior rank and vest accordingly. In "traditional" communities, it still happens.