I'll toss in a couple comments here...
My wife is pretty tiny. Roughly 5'3" and 110#. She's been shooting shotguns semi-seriously for a few years now, and we went through some trial and error getting her going.
Basically, for a smaller shooter there are two different things that have to be balanced. One is recoil, the other is overall weight. For my wife, we've found that recoil is secondary, and that overall weight tends to be more of an issue. In general, she would prefer to shoot a lighter gun that kicks a little harder, than a heavier gun with light recoil.
Actually, I just lied... as there is a third component... ease of operation. In particular, some brand-new O/U actions prove to be so stiff that she has trouble operating them smoothly. A broken-in piece is no problem, but she really dislikes having to wrestle with anything on the trap line or in the shooter's box.
What we ended up doing was going with an autoloading 20ga for a while, and then moving to an autoloading 12ga. With the move to the 12ga, she started scoring better (for more than just gauge reasons... but that's another issue), but she felt more comfortable starting out with "her little gun". She's been eyeing O/Us with a disconcerting amount of interest lately, though...
Please note that bruising is not normal in most cases, and that it can be remedied most often with proper attention to form and utilizing the lightest available loads (no more than an ounce and at moderate (1200fps or <) velocities).
The important thing is that shooter's have to find what works for them. Some people will dislike recoil more, others dislike overall weight. If you are minimizing recoil, a gas-powered auto with light loads and a good recoil pad is hard to beat. In any event, the gun is going to have to fit. I worry less about LOP, as most stocks can be cut down and fine-tuned. When looking at youth models in the past, it seems like they will often come with a shorter barrel-length as well. As I prefer long barrels for anything aside for HD, that makes them less useful in my opinion.
My last piece of advice is to have her try a lot of different guns and see what she likes. Let her pick it. Let her pick it. Let her pick it. Let her pick it. There, was that subliminal enough?