Nes Suno , Dec 08, 1997; 10:34 p.m.
The Lowepro photographer's backpacks look to be optimized for the hiking photographer, not for the camper/hiker with a ton of photography equipment. (Check out the images on their web site, call for a catalog, or go to your local pro shop for a hands-on inspection.)
There are ample ways in protecting camera gear without resorting to a photography-only backpack. In your case, I believe you will be hauling too much equipment. 2 cameras (3 lbs.), 3 large zooms (4 lbs.), 2 primes (2 lbs.), large 300/2.8 (6.5 lbs.), Gitzo 1228 + light ballhead (4 lbs.), film (1 lb.), filters/lens cleaner/hoods/etc. (0.5 lb.) = 21 lbs. nominally.
If my web browser is correct (http://www.lowepro.com), the Super Trekker AW itself is 11 lbs. 11 oz. That's a 32 lbs. load on your back and you don't even have a handkerchief. If you can get your sleeping gear, clothes, 4 days food/water, etc. into an 8 lbs. package, then go for it.