I also would just take the photo with a ruler in the shot or probably just use Photoshop and use the rulers on the page. There is NO requirement to take the photo with a certain lens since all the print sizing can be done in post-processing.
In fact I can try to print it for you if you send me the image file and tell me the dimension of the toy. Because really it doesn't matter how big or small the stuff toy is relative to the frame. The smaller it is it would have less details but the size can still be printed correctly.
Why not make it simple -- put it on an 8.5x11 sheet for the photo, then print to fill the same size printer sheet with the image of the piece of paper?
Why not make it simple -- put it on an 8.5x11 sheet for the photo, then print to fill the same size printer sheet with the image of the piece of paper?