Hey Richard,
According to the site… they are using “dry pack bags” designed by ULA Equipment. I’m guessing they were custom designed and built for the trip. I love my Gossamer Gear packs… but no way would you take something like that for a trip like this! See… lightweight is not about lightweight at ANY cost. If it were… there’d be a lot of dead ultralight backpackers out there :)
Also… just to point out… when we talk about “base weight”… that’s not just the “big three” of pack, bag and shelter… base weight is everything in your pack BEFORE food and water. The big three is a big part of that… but it’s not everything. Adding in your pad, clothes, kitchen… etc… all adds up. My “luxury” base weight for a sea level boreal forest 3 season hike is 7 pounds… that includes a cot (yes… a cot) and a pillow!!! Very luxurious!! Of that… 3.9 pounds is my pack, pack liner, pad, cot, shelter, pillow and sleeping bag… my “big three”. The other 3.1 pounds is clothing, kitchen, first aid, toiletries, etc.
I agree that superior frame / suspension can make heavy loads seem lighter. Just before I went “super ultralight”… I almost bought a 6 pound monster pack from North Face for it’s very cool pivoting suspension system… that allows the pack to move with your hips… and would make heavy loads seem much lighter… but instead I went ultralight… and now I can create an entire kit… minus food and water… for 5 pounds!!! Less than the weight of that North Face pack when empty! The point being… with 10 pounds of food… that’s still only 15 pounds… and with that little weight… suspension really doesn’t matter.
But yes… for really heavy loads… superior suspension can make a world of difference. I did a couple of years of 40+ pound backpacking before making the switch… so I have a little bit of experience with heavier loads. Not as much as you… but some… and I certainly did notice a difference depending on what kind of pack I was using.

