OK Let's get back to it today a bit. I asked the forum member what kind of LP neck he was interested in and I didn't get a response yet, so I will do the standard lp neck with the 16th fret joint.
In Rhino, using the centerline I drew a rectangle for the peghead material.
I think it is 4" x 8". I also drew a 1.5" wide by 3" long tenon.
I drew in the nut of 3/16"wide by 1 11/16" long.
I measured down the distance to the 16th fret. It rounded up to 14.82 on the dimension itself, but was the distance from the stew mac fret calculation.
I also added a line under the fretboard edges, since I will remove the fretboard from the drawing in the next step. You can see the tenon lies within the confines of the fretboard. This is the more modern tenon, if you wanted the long tenon which extends into the neck pickup cavity, you can draw it longer if you wish. The steps are the same. All these lines are projected to the cutting plane, so they are all at the same level in the other views.