Speed wing extensions

I have just recently extended my C model speed wings. I removed the
Original wing bow tips and added 48 inches of lift to each wing with
flat tips. The situation now is I have a good bit of wash out. Enough
to where when the tail of the plane is lifted to where the she would
be in level flight, the wing tip actually has a little negative angle
of attack. The plane flies fine but a little more tail down than I
like. My next thought is to remove the extra 12 inches of wing to
reduce the negative angle a bit. Anybody out there got any
constructive experience or ideas, I be interrested to get your
opinion.
Thanks Walt