I am re-making the (torn, worn-out) dust jacket for a large book. I have scanned the old dust jacket. (It took three scans, stitched together like a panoramic photograph.) I repaired the worst of the damage with photoshop, and now I am trying to print the repaired cover image on good new paper using Xnview. I have a wide carriage printer (Epson Workforce 1100) but even so it's going to take three printer passes on three pieces of 11" x 14" paper. Sticking the pieces together this time will be done with sticky tape

The old dust jacket is exactly 11" high. That is the short dimension of the front scan. The long dimension of the image, when printed, is the full width of the front (8.5") plus the front fold-inside part (3.5") giving 12" total. Printing this image works exactly right if I set Xnview to print best fit to page, "automatically rotate picture (if needed)" checked, and with left and right margins = 0 (and the printer set to do borderless printing in Epson's driver software.) Printing the back of the dust jacket (plus the rear fold-inside part) this way works exactly right also.
The problem is the repaired image of the spine. Because it is tall and narrow, Xnview thinks rotation is NOT needed and so it wants to print with the long dimension of the image the same as the long dimension of the paper, instead of across the paper. So far I have been unable to find settings that print the spine image so that its size exactly matches the other two pieces it has to match. It always comes out either slightly too long or slightly too short. (The old jacket had fold-around graphics, so even minor mismatches are obvious.)
Question: Is there any way to ask Xnview to print the spine image across the 11" paper with margins set to 0, as the other two parts of the new dust jacket were printed? Or is there some other strategy I've overlooked that would give the outcome I need?
Thanks very much for any advice!