I usually call my friend in Arizona to help me with this sort of thing. Do you have reasonably sophisticated photo editing program? I would think it would be easy to slice the image into 2" pieces and then space them.
The other thing is if you print multiple images you can get a couple out of each one, so you might get rows 1, 3, 5 all in one go, then cut 2 and 4 out of the other one.