Hi Phillip;

If you're putting on an external stem, just shape it so the point on the stem sits on the hull centerline. It will be noticeable when the boat is upside down, but no one will see both sides at once to compare when it's right side up. You might even want to plane down further, to perhaps 3/8" wide so the imbalance in shape is less noticeable yet.

You can see my bow & stern stems at the link below under "Hull Construction." BTW, I couldn't see your picture, I hope I've understood your problem properly.

Good Luck, Spidey