Well, if it can't be about the upper body, and it can't be on the legs, and it can't be a waist bag, that leaves the little red wagon, right?
Movement of the shoulder bag can indeed be a problem. Another strap to go around the waist or lower chest might solve that one. A back pack or book bag worn backwards, perhaps?
If this is to be a rig for every-day carry, rather than just for this (and similar) training course, I have no idea what she would want or accept.
Pops