I'm not a big fan of the camera thing. The main challenge is lighting the piece evenly, without specular highlights or hot spots. It's also preferable to use a flat field macro lens if you use a DSLR, and that's not cheap. You might try stitching smaller flatbed scans with a pano tool:
https://havecamerawilltravel.com/photographer/scan-oversize-images
I'm looking for the scanner specifically for some artists I know (three of them) at what amounts to an art studio / artist meetup, and at least two of them scan artwork almost daily, and often work in A3-ish sizes as well as 'regular' (for me) letter-sizes. The scanner I'm replacing only scanned letter/legal sizes, so the artists have had to frequently stitch larger artworks together, and no longer wish to if it can be avoided. I've also, on more than one occasion, have stayed up entire nights scanning piles of artwork (30+ A3's) and stitching them together in Paint Shop Pro (the art software I use). It's easy to do (and the artists normally do it themselves), and the quality comes out plenty fine, but it's an annoying waste of time for any of us.
Since A4 artwork gets scanned pretty much all the time, I'd love for a way to make that task easier.
Good idea about looking for a software solution; thanks! I'll look into panorama software that might automate the process. If I can find one that basically does it automatically, and install them on each of the artist's computers, perhaps manually adding it to Window's context menu, then it could be as simple as selecting two or more images and doing Right-click -> Stitch Together. If it automatically works well, nine out of ten times, I don't think anyone would complain about having to fall back to manually stitching them together once in awhile.