I used jigs to move flat art for stitching while leaving the camera stationary. Even when using a view camera, I found that moving the art worked out better than shifting the rear standard. Using the Hasselblad multi-shot back was great for 2 1/2 D--it had enough acuity to dispense with moving the camera or the art.
How's about a sheet of OSB/ plywood, with a frame on the back for rigidity. Attach high quality smooth wheels to the bottom, roll it side to side on a long level. Use the level's distance markers to get consistent spacing. Attach the art to the OSB/plywood.