Rooms: id, name (has_many :rentals, belongs_to :units)
People: id, name (has_many :rentals)
Rentals: room_id, people_id, created_at, ended_at (belongs_to :rooms,
So Rentals is a join table between Rooms 6 people, correct?
has_many :people, :through => :rentals
has_many: rooms, :through => :rentals
that should enable you to do @unit.rooms.people