there a way to let customers choose from a variety of different
templates AFTER they have selected a product and clicked the
Customize Order button? Think Homepage > Business Cards > Full
Color Business Card (Product Page) > Customize Order > view and
choose template to edit at this point.
can create an eDocBuilder template and, using the Image Picker
feature, let them choose from a variety of backgrounds. The merge
field layout and locations would be unaffected and unchanged. If you
are using the Interactive Designer, you could also let them move the
text fields around so they can adjust for the different designs.