You could create two "Finger"-sprites which are controlled by the thumbsticks and have the plate either pinned by location only, or via physics revolute joint, or just set the angle of the plate to angle(fingerleft.x,fingerleft.y,fingerright.x,fingerright.y)
Issue with the first two solutions is ofcourse that the plate becomes shorter in the horizontal direction when the angle get's bigger, but there are multiple ways to take that into account..