You can most likely correct this problem very simply. Half fill about a dozen sandwich bags with sand(dirt will do). Measure the warped distance(work surface to the lifted wing tip end TE) and make a shim from a hardwood strip or plywood this thickness. Using a misting spray bottle, dampen as much of the wing as you can(skin, spars, ribs, etc). This is not a soaking, but just enough to lightly dampen the wood. Now on your building board or other flat surface like a kitchen counter top, place the shim under the outboard leading edge. The sand bags are now placed so as to keep all four corners of the wing against the flat surface as the wing dries. When the wing is dry, check the amount of warp remaining. You may have to repeat this procedure a couple of times. I usually have to make my shim about twice the thickness of the warp. It seems the amount of twist removed is usually about half the shim thickness. When I mentioned above to use a shim the thickness of the warp, this is for the first try. You will see the wing should start to straighten and on subsequent misting/shim/drying tries you can adjust the shim height as needed.