-I would definitely not try to split that tiny little white stripe - it will be almost impossible to make it look good.

-I also wouldn't hold the white stripe up the edge of a pleat - the white line is a pivot, and I think it looks odd when the pleats on each side of a pivot are not mirror images of one another.

-Another thing you should try is pinning up the pleat at the actual size and taper. The black stripe is dark, as is the adjacent green, and it might actually not be all that obvious if you lose the stripe in the taper.

-Paul Henry's solution is a good one, and you could choose to make the pleat with the white stripe either wider or narrower than the others. Try a test pinning first to see how you like it, though.