Advice is always wanted and welcomed, John. I'm in Michigan now; I moved away from Iowa where my old instructor was. So the reason that gap is there is because the entire panel actually has an outword bow/curvature to it, rather than being flat. This is fine and all except for the ends. It's like the panel needs to be stood on and smashed down flat. Not that that would ever be my solution,but to give you a visual of the problem. Width-wise the panel is fine. I only tell you this because the picture can be deceiving in that it truly doesn't reveal what the problem is. With that being said I don't know if that changes how you would attack the problem or not.
If there's any single place where I've become really smart in my body work it's been knowing my capabilities and knowing when to stop--or not even start. In so many instances my good intentions have only made an issue worse. In this case I was willing to live with the gap rather than try to fix it and create a worse problem for myself. I don't want that to stop anyone from suggesting solutions though.