I don't think you could make a better choice in a thru-hike lightweight, but durable, pack. The Vapor version is identical to the Nimbus version except the suspension isn't as robust. Other than that it uses the same materials and construction. The Nimbus Meridian was used by Justin (aka. Trauma) who hiked, in one year, all three major thru-hikes (AT, PCT, CDT) and even did the extended version of the AT (from Quebec to Key West, FL)! This he did with only one pack and the only damage was a small hole in a side pocket put their by a hungry rodent. All in all, he hiked 10,000 miles in about 364 days (averaging 30 miles a day). I've checked this pack out, and although it is discusting because all of the sweat and salt stains, it's in almost perfect shape!

The Nimbus Meridian is the only pack ever made to make this claim. The Vapor Meridian is up for the challenge!

You could get away with that depending on the width of the board. However, because of the lightweight materials, it isn't designed to take the abuse of the snowboard's edges. A better option may be the Granite Gear Flash due to it's much more durable materials. It uses the same suspension as the Vapor Meridian and they do have a women's version. I would check out http://www.granitegear.com/products/backpacks/ultralight/vaporflashki.html for more details and to find a dealer.

I don't think you really have to stick w/ the old rule of thumb of not carrying more than 1/4 of your body weight. I did 10 days in the Alaskan bush with pack weight of over 45 LB, and I only weigh 110 LB. I did fine w/ a 6.5 LB arc'teryx pack with an excellent suspension. I think you are probably fine to push the weight a bit more to like ~33 LB, and really need to make sure the pack has a good suspension that efficiently transfers weight to the hip. I agree w/ the other commentor that you will need to pack energy dense food, achieving something like ~130 cal/oz (try Probar for example). If you do that, you can budget for a little over 1LB of food per day. Use a lighter sleeping bag and sleep w/ all your clothes on. Ditch the water filter, use a 0.3 oz micro light rather than headlamp, etc. Check out backpackinglight for tips (I think a lot of their weight saving strategies are excessive, but their forum does open your eyes with additional areas that you can save weight).

btw, i think the osprey women's stuff tends to fit a bit smaller relative to other brands.

Also, there is a guy above who posted that this is perfect for him and he is 5'11" and 165lbs.

A week of food? As a very general rule, food comes to about 1kg (2.2lbs)/person/day. 7days x 2.2lbs = 15.4 lbs. I have a friend who hardly takes any food on such a trip in order to diet and come home 10lbs lighter. How much water will you need to carry -- 1L=2.2lbs? I am 5'5" and 110. Have the same concerns as you! 59L should be plenty of volume. I think to get the weight down to 25 lbs, you might have to ditch the cooker, mat, and live off very calorie dense energy bars, bring a tarp instead of tent, etc. I sleep cold and need a bag down to 0F to handle freezing temps. I recently did a weeklong winter trip starting with over 50lbs -- though I did have snowshoes = 4lbs. Also remember the old adage that a pound on the feet = 5 lbs in the pack.