hmm, i think it depends on what you want to use them for, for touring, i would feel more comfortable with panniers that are made for the job. that being said, i do think it could work if you rigged it up right, i would try to mount them a little farther back than normal panniers and hang a bit off the back side of the rack more to account for the extra length

you don't want too much weight too high either, so if you could mount them on the front wheel (to keep them lower and more accurate to what real panniers would feel like) i would