Required Characteristics?

I'm curious to know if this is possible, I really like how Characteristics work, more specifically how they change the items main image as I select the different options, If I could set this option as required I would be able to provide a visual confirmation for a customer as they select a product.

This would be also possible with "Custom fields" since I can set those to required, If only I could upload an image per value (single drop down in this case) but my guess is that would be more complicated..

At the moment I'm using a work around where I just set one of the characteristic variants as zero stock which removes the "add to cart" option on my item page thus forcing the customer to select an option, But I figured I'd ask and see If the above was possible just out of curiosity