Paul,
I use CuteEdit to allow my client to send emails. I actually even wrote a mini scripting language to allow replace of names, address,etc similar to how word does merging, but the merging is done outside of CuteEdit. I only allow CuteEdit to create the content, and not the html headers around the email so I have better control.
On the idea of the table, you could create your own template, the template would be a simply a table with a single row that would be house the content of the editor, then by use of css apply the image to the background of the table thru a class element or the more direct method of a background element.
RC