Texture mapping?

I’m having an issue positioning an additional texture on a surface. The UV of the surface is slightly curved and its difficult to catch it exactly in photoshop as the back is where the seam is.

Is it possible to create a separate straight image and map it directly to the character’s back without its UVs?

You can have more than one UV map … You can use nodes (most easily) to associate more than one texture with an object, such that each texture has its own influences upon the pixels of the object.