RE: Trailing edge slightly upturned at wingtips?
I'm trying to imagine the geometry of this. It seems to me like you mixed in some dihedral with the washout by upturning the TE.
I think that the geometry of the wing you have made would be the same as a wing with added dihedral, with the LE drooped down. Think about it. This will add some more (possibly unwanted) lateral stability.