I have worked with panoramic capture/stitching software for the past ten years and would still never recommend using it for copy work - certainly never as a first choice.
By your own definition you require a space twice the width and twice the height of the original just to be able to slide the subject L-R into place each time. Then you raise the shelf to move the subject into the copy position for the next series of passes. That sounds like you need a special moveable shelf. How do you hold the artwork absolutely parallel to the film plane? Would you describe this as practical for the average Joe in this forum?
It seems like such a massive amount of work with so many opportunities for error. One single incorrect exposure or something not noticed could result in having to repeat the whole series of images. What if the original is rolled and needs to be held flat with glass? I would equate your method to producing photocopies of different sections of the original and then laying them all together to make one whole. Lots and lost of overlaps and joins to be attended to.
Ordinary panorama stitching software will not necessarily work either because of the tendency for it to try and introduce or correct perspective by adding barrel or pincushion distortion.
Of course, whilst it might appear to work well how can one be certain that the software has not tweaked something that you simply do not notice at the time. The software is making the decisions autocratically and that, to me, means you are not - so errors can creep in. Every single 'frame' will bear any lens distortion so this will be present at each and every stitch. A straight line could easily end up as a wavy line under these circumstances and software would be none the wiser. I work every day with images perhaps 16 metres wide by 5 metres high so a straight line has to be straight.
The sheer amount of time required to then check the image and all its overlaps making sure there are no ghosts or masked elements must make this cripplingly slow and arduous. I suspect most on here would not wish to spend so much time on the task when there are simpler means available.
In all, this is not a straight forward method for fast copying or for anyone who just needs a good copy with minimal fuss. I was stitching images using your method almost 20 years ago.
The 105 is indeed a useful focal length and falls within the range I would personally suggest to maintain a flat field. We are talking full frame sensors of course. A genuine test for your method would be a very large checkerboard which would fully challenge the software and the setup.
But I suspect the majority of people on this forum find copying something of a mystery and are seeking solutions where simplicity will be the key. My method is not 'my' method but one I know to have been used by thousands of professionals preceding me and one I have also handed on to thousands of trainees over the years. It is based simply on the industry standard Process Camera setup - tried and tested by every print studio for decades when lith film was the basic copy material. It does not require the purchase or use of softboxes and can be adapted to cope with images as big as a wall. At a push, two similar domestic lamps could produce reasonable results. You don't even need a tripod because you can rest your camera on a table and cellotape the artwork to the opposite wall!
It is always of interest to learn how others have adapted and evolved processes for copying so I wish you continued good luck with the results. I did not mean to offend you in any way and I too respect the opinions of others but I still stand by my statement - you do not need to treat your image as a panorama.