Wow, I'd never have the patience for that.
Have you tried making the front pic larger to cover more of the front, even if the sides get chopped a bit? You could also extend that front pic onto the spine. I realize covers are usually looked at as 3 separate parts, but with a gorgeous image like that, I'd rather see it flow onto the spine instead of having a spine that doesn't flow with the back or the front.
You could even move the "grass" on the back down so that it looks continuous from the front.