Front and back for print store: Required 2nd product by attribute

I'm starting a print estore based on templates and have the option for two-sided printing, so after a customer chooses their front image and have added it to cart, if they have selected the 2-sided attribute, ideally I think I'd like them to be redirected to choosing the back "product" to add to cart for $0.

I considered adding this as another attribute option, but I plan to have about 50 or so back templates to choose from, so it would be a little silly to do it that way.

Looking for any suggestions anyone may have. :lookaroun

Testing at http://www.wholesale4realtors.com/cart
Using Zen3.8, modified default template, no major mods added.

I had a thought on this... Is it at all possible to have a page 2 of a product details before checking out (2 step process)? :huh:

For example, regarding business cards, everything on page 1 of the product decription would be regarding the front of the card, and instead of add to cart it would have continue to step 2, and the second page would be back options with the add to cart on that page.