I’ve got the old cheap Canon 100mm macro I’ve been using with my Canon 5DIII. Read via Nate’s post that he doesn’t recommend using adaptors and I could see it would be a little tricky.
I just think framing up the images would be a lot less trouble for my neck as I’m framing.
Also the T30 I find is less clunky for any long exposures, lighter and easier to secure on a tripod.
Also looking for the right LED panel as my iPad 2 isn’t ideal.
Using the 100mm lens on an APS-C instead of FF camera will increase the distance between the negative and the camera, also increasing the want for a giraffe neck 
a flippy screen can help though.
I’ve taken shots with the gear you mention, but with an EOS M6 instead of a Fuji. Both combinations work well on a copy stand type of setup. You could get an alternative setup using a black round table leg from a hardware store and a clamp like so instead. Use mirror lockup or live-view and the self-timer to reduce vibrations.