You've had lots of advice, you just dont' want to listen. You want to debate with people that have far more knowledge than you do about the merits of your selections.
Here is what you should do-
Get at least one of Gary Sheltons books for her to read.
Take the stupid pistol grips off your 870, and install the regular forend and buttstock.
Get some 2 3/4" trap loads
Take her to range and get her comfy shooting those, preferably at milk jugs or something reactive, so she can see what she is hitting.
Swap to 2 3/4" slugs and get her to practice a few of those, probably no more than 3 or 5 per session.
Track down some 2 3/4" Brenneke or Challenger slugs if you can, for her to use when she is working. They kill better than regular foster style slugs. 2 3/4" slugs will kill just as good as 3", but with less recoil.
Quit pissing around coming up with stupid tactical folding stock M-305 bulls**t solutions. If you want to play mall ninja, go for it, but not at the expense of her safety.
A simple shotgun that she has fired 100 times with trap loads and 20 slug loads will work better for her than any pistol grip ninja gun or combat stock 305 or whatever....
Sounds like a plan, I was thinking of dropping in 2-3/4 shells anyhow, my winchester holds one more of those than a 3" and it would tone it down a bit as you say.
But I'll let her decide weather to use the pistol grip or not, If putting the stock back on means the gun will be leaning against a rock, then I guess its better being off. however she will have to give both an honest try before she decides. in light of your considerations, I can see your point, I suppose I would strongly advise she keep the stock on, I don’t really like it for target shooting, but when it comes to only a few shots between life and death, its better to have maximum three point stability. ("OMG he actually gets it, I think I'm going to F'-ing die!!!")
As for the mall ninja remark, I'm not a mall ninja, I don’t wear cammo or surplus except when I'm playing air soft, and that’s only because the guys I play with are mall ninjas, well some of them anyway, and its their air soft dress code.
As for my rifles, I like tactical because its so compatible with any device under the sun due to its picatinny rails, and compact so I can move freely without hangups while hiking in dense bush, and also aids in carrying it in a small duffel bag or back pack, to keep pulses to a minimum. I’ve found the presents of any gun make non gun owners uneasy. I’ve even had on guy tell me "If a bear attacks me don't bother shooting it, I don't want to end up getting shot!"
To that I replied, " Okay, I'll just run away and let it eat you alive..." hell it works for me, I’m not complaining.
I would love to send her to defense training facility, but she’s a farm girl, and no doubt she would think she wouldn’t need it, with her competition shooting back ground and all. And her dad has a history with defensive firearms use from back when Canada was not a dull place to live. He's certian to have given his girls a few pointers. But thanks for the suggestion. I do appreciate it.