That's a lot of gear for a light weight pack. I have a 3 lb pack that's rated for 40 lbs at most, and it's not comfortable with that much - I only did it on a long trip, as the gear I have stays the same, it was only the food weight that increased, and within two days the weight dropped to the point that it was comfortable again.

And my pack has a sturdier frame than any of the packs you're talking about.

It matters a lot to put your gear in the pack - it matters to be able to balance the load properly within the pack, which you cannot do with pillows and sand bags. You need the bear canister and the rest to fit in the pack and have it ride comfortably. The only way to test that it works is to do it with the gear you intend to take.

I started with a North Face Terra, moved on to an Osprey, and landed firmly in Granite Gear when the first two failed for me. It needs to work without discomfort. Trying it on in stores did me no good and I ended up selling them second hand, because I did not take in my gear and try them out.

Don't skimp on pack suspension if you are starting out heavy - Granite Gear is IMO a good bridge between heavier and lighter loads as you are working the weight down. Another one you might look at would be Deuter - not as pricey as Osprey etc but a decent suspension system.