What you are doing (moving your weight towards the center of the board to lower the lee rail and
get more vertical lift from the centerboard) is precisely what I've done and have seen done in
longboard and one design racing (boards that have centerboards).
Sometimes, depending on the width of the board and the sailor's weight, you need to move your
feet to the downwind side of the boards centerline to really "rail it" most effectively.
So, keep doing, what you are doing!
Makes a racing longboard go upwind like crazy if you "rail it" and move the mast foot forward to
engage as much lee rail as possible.