Check out this web site
- Integral Designs - Innovative Gear for Self Propelled Adventurers they have some top quality gear. I used one of their bags on a sheep hunt in NWT last year and my guide slept under one of their tarps. Very light weight high quality gear. It is also expensive. My 0 degree F down bag is waterproof, but it cost over $600. It should last a lifetime.
Backcountry.com: The North Face, Mountain Hardwear and Patagonia Skiing, Camping, Hiking and Backpacking Gear from Backcountry.com Camping MSR, Sierra Designs, Hiking, Skiing K2, Volkl, Climbing Petzl, Yates, Snowboarding K2, Palmer, Rescue @ HermitsHut.com
Here are a couple more. The mountaineering folks really know light gear and how to survive.
I use a Mystery Ranch pack and really like it. I agree a frame pack may be alittle better for big meat loads, but I would much rather hunt in my MR internal frame pack and think overall it is a better deal. I have the NICE frame MR pack and can change bags from 6500 inches to 5000 inches or use the crew cab for day hunts or even overnight hunts.
Welcome to Mystery Ranch Backpacks The pack bags have a place for water bladders.
Good Luck in your search.