Improvised and Shop Made Neck Jigs

[PSmill]

Hi, I posted a week ago about how to best level frets on a classical guitar with a slight neck relief (0.008") with the strings off. No truss rod. Coming at this from another angle related to building tools, I'm thinking of making a temporary neck jig (ie. the Erlewine neck jig device), by placing a tall caul under the middle of the neck (the bottom will sit on the bench), securing the body, and then applying very light pressure pulling down around the nut/headstock, to straighten the fretboard.

I am wondering if people are using neck jigs for levelling, and if anyone has plans or measurements for a good shop made or temporary setup? Thanks.