Old thread, I know, but I was fighting the need for a plate bracket too. Read somewhere on here about "plumbers strapping" which instantly made me think of my extra metal drywall corner piece.
Cut a piece to length (plate length), folded it in half, drilled 4 holes, mashed it nice and flat w/ a 4lbs. hammer and attached it to the agility with two plastic ties. Seems good to go.