I can't offer more than general advice simply because I don't backpack in areas where a canister is required. I did do a lot of research on packs 2 years ago when I was lightening my load and ditching my 5-lb. Kelty external frame pack, so what I'm describing is based on my research at that time.

I can offer the advice to go someplace besides REI. My experience with them (the downtown Portland store and the "flagship" store in Seattle) is that they carry only a very small fraction of the packs that are available, with less variety each year. (Sorry, my antipathy to REI is showing!) I suggest you try specialized backpacking/mountaineering stores in your area--they might just have something or be able to order it for you, and at least here in the Portland area they were a lot more skilled and sympathetic with my needs than the clerk at REI. I ended up purchasing through the internet. The main problem with that, of course, is that you have to pay the shipping cost to return it if it doesn't work. I felt it was worth it to get the pack I wanted.

I found in trying on numerous packs that quite a few "unisex" packs worked just fine for me, although a lot of them don't. This may not be true for you--I'm female and short (5'3") with a 15" torso but have shoulders (and, unfortunately, hips) that are definitely broader than the average person of my height. But it's certainly worth a try. Like you, I suspect that there is a lot of sexism involved in women's gear, and not just the horrible "Bink and Burple" colors they come in. I wouldn't be surprised if the manufacturers do expect that anyone wanting their woman's packs will have a man to carry the bear canister. More likely, though, the idea of a woman's carrying a bear canister probably never even occurred to them!

I ordered, as my first choice, the Six Moon Designs Comet with the optional stays. It was my first choice for several reasons--it has load lifters, it was the lightest of the packs that met my specs and it's made by a local (for me) firm so I wouldn't have to pay shipping costs. I adjusted it down to its shortest torso length (15"), loaded it up with all my gear and the equivalent of a week's food, and it fit as though specially designed for me! That doesn't mean, of course, that it will work for you! It would carry a bear canister, I'm sure horizontally although it might have to be inserted vertically and then turned (the extension collar is slightly narrower than the rest of the pack). I'm going to visit my youngest son's family after Easter and can test it with his Bear Vault 400 if you're interested. I haven't tested the Comet's load limit--I've been up to 29 lbs. (sherpaing both for granddaughter and sick grandson) and that was definitely the limit for my bum knee hiking on loose sand (beach at high tide), although the pack itself felt fine. That occasion was the only time I've completely used the extension collar. My only complaint was that after a year some of the stitching came loose (nothing critical, though; in fact, it looked suspiciously like a basting thread). Ron Moak fixed that for free. I believe this pack would be worth your checking out--you might want to give Ron a call.

Like others here, I also suggest that you call Brian Frankle at ULA, talk to him about your problem and see what he can do for you. Based on his reputation, I would have gone there first except that with a 15" torso I was limited to the Catalyst, which was a little heavier than I wanted (it was #2 on my list, but since #1 was perfect for me, I never got that far). I suspect the Catalyst might be a little better for your needs since it's a little bigger and can carry more weight than my Comet.

Good luck!