The cutting of the neck photos didn't work well enough to show, but you've probably seen someone cutting before. I used a no11 exacto blade to score the line I drew on the fretboard, then bevelled that cut, then sawed with my japanese fret pull saw.
The white clamp is my 3d printed luthier clamp I made some time ago. Wouldn't keep a 20 year olds' erection down, but works for keeping this kind of thing from moving. ;-)
I just used some clear contact adhesive to glue the two disparate materials together, not the best idea I've ever had but it will glue them together whereas the other glues I have to hand are unknowns and not worth gambling with.
I'm going to use the probable weakness in the neck to give its own relief as its put under tension by the strings.