She's been playing for 3 weeks now and is making good progress.
It's funny, she's immediately figured out what she does and does not like about basses, ergonomically. I'm super picky about bass ergonomics myself but it took me 20+ years before I figured out what I really like and don't like and another 10+ years of hemming and hawing over it, which leads us to now
The JMJ Mustang is good in the sense that it has a small body but it sounds like the neck being thicker front-to-back and rounder in the fingerboard radius. She really liked the wide flat neck of my new Roscoe PJ Classic Custom (1.75" at the nut and thin front-to-back with a radius that I assume is 10"-12" but I'm not sure.) It's funny to me that she has tiny hands but liked the 1.75" nut width. "Forces my fingers to stretch," she said. She also liked the Roscoe's relatively flat body though the overall shape was still pretty big for her. She did NOT like my Musicman because the body felt huge to her. She also did not care much for my G&Ls.
Bottom line is that I've determined she needs a Spector with a Lakland Bob Glaub neck. How do we make that happen?