The ULA Catalyst (not quite 3 lbs.) and the Six Moon Designs Starlight and Traveler (with the "optional"--mandatory, IMHO--stays, 30 oz.) do have frames--including load lifters, which my pressure-sensitive shoulders insist on--and are quite comfortable up to 35-40 lbs. The two SMD packs run about 30 oz. each. If I can carry 35 lbs. in an SMD pack (the discontinued Comet, in my case) without discomfort (well, my knees and feet were unhappy, but my back, shoulders and hips were fine), so can you. One of those SMD packs would save you 2 lbs. right there.

Should you try hiking the Rockies (my suggestion would be Wyoming's Wind Rivers which you can hike end-to-end on the west side or do cross-country exploration--check with Wandering_Daisy, our resident expert), you'll definitely need a warmer sleeping bag. Snow and temps down in the low 20's or even high teens can happen any time during the summer.