Sorry if I seem a bit dense. What is the final presentation method and size? If the final size is 12x16 (not matted to a larger size), it will be difficult to get a real clean presentation (IMO) since the proportions of the (full-frame) image and the paper are so different. It would work better for vertical images than it would for horts.
That said, I prefer several inches of border around images. On a 12x16 paper, a 7x8.75 image gives one 2.5 to 3.5 borders, which would be my minimum. But an 8x10 does give one 2 and 3 inch borders, which is not too bad.
For an informal presentation, Adrian's suggestion of a 10x13 image size would give sufficient border for handling the print.
Vaughn