I'm a couple inches taller than your GF but have exactly the same torso length. I also happen to be the only woman who has responded here so far, and you'll notice that my advice is different!
One thing about being a woman is that our bodies and our pack requirements are generally different from those of most men. I personally have extremely pressure-sensitive shoulders, so I require some sort of frame and load lifters in order to keep the straps completely off the tops of my shoulders and transfer all the pack weight to the hipbelt. This rules out a frameless pack unless I'm carrying 5 pounds or less. Even that small amount is uncomfortable for me without a stiff foam back and a well-padded hipbelt.
More important, a woman's center of gravity is normally several inches lower than a man's. This means that if there is not adequate weight transfer to the hipbelt, which requires some kind of frame, the pack will be top-heavy and pull her off balance. This is another reason to avoid a frameless and hip-beltless pack like the ones you're looking at. That means your one pound weight limit is probably unrealistic if you want her to be comfortable. There are lots of packs with some kind of frame that weigh less than two pounds. .
My current pack (Six Moon Designs Comet, with the "optional"--mandatory, IMHO--stays) has been discontinued and SMD's nearest substitute, the Starlight, is far too big for me (it's 60L; I've never gone over 40L even when sherpa-ing for grandkids). I have found the Comet wonderfully comfortable and have carried upto 37 pounds in it. My shoulders, back and hips were just fine even though my knees and feet were screaming---I won't try that again! Normally my maximum total pack weight is 24 lbs. for a 9-day trip. It's 15 lbs. for a solo 3-day trip if I don't take fishing gear. My pack alone is 27 ounces.
If I were replacing my current pack, the first packs that I'd look at would be the Elemental Horizons Kalais (with the so-called "optional" stays) and the ULA Ohm 2.0. Both are under 2 pounds, are available in my (and your GF's) short torso length and can be gotten with the "S" shaped straps which for most women are far more comfortable. I can get along with a unisex pack (which mine is), but having tried the "S" shaped straps, I definitely prefer those. Both these packs come with 15" torso length. Elemental Horizons will also customize the Kalais for your GF; just ask them! The ULA Circuit (heavier, but more supportive) comes in a youth size which has an adjustable torso length; with the "S" straps this pack might also be better for your GF. It's too bad they don't have this option in the Ohm 2.0 (it wouldn't hurt to ask, though).
Be sure your GF has all her gear (including water, fuel and the equivalent in weight and bulk of food) ready when the pack arrives, so she can load up the pack, adjust it and "hike" around the house for a couple of hours. This needs to be done (keeping the tags on and the pack clean) while the pack is still returnable, usually within 30 days. It's important to do this with her actual gear; weights are not an adequate substitute.