Update on this project, I am now using the 4.9.0-3-rt-amd64 PREEMPT_RT image and with regular apt updates it is still working well.
I have not made another ISO as I didn't think there was any interest and it is only a play for my own benefit.
I have installed librecad, autotrace, kolourpaint4 to demonstrate how good a Linux alternative is to the other options.
I still can't convince my prospect who loves his fancy gui but doesn't know how to use it.