If she wants to carry OWB on her hip...talk her into using a belt. A secure pistol is a happy pistol.
My wife wanted the same thing when we're out "woodsing", 4-wheeling, camping, etc... I told her its best to use a belt...she said she complained and didn't want one, I showed her how the sloppy positioning of a tension style holster doesn't like to release as the angle cants due to lack of stability. I also told her to jog in place and she would see how OWB magnifies the weight of a pistol. Eventually she saw things my way but my wife usually wants the impractical.
What holster did you end up getting her?
Shoulder holster
Glocks
maybe this will work
Tell your wife to man up and wear a..............wait....er..no.
I actually thought about that since most 20 somethings wear jackets and looser fitting cardigans. However I'm not sure I like the idea of her using a cross draw. Isn't cross draw dangerous? Shooting yourself in the midsection? She isn't as experienced as she needs to be, but if I do get her a shoulder holster and some snap caps to practice. Do you think that would be enough?