Since you're in STL, check out REI's Gear Sale still going on. They may have some cool stuff in store for you, or at least at their website and you can have 'em ship it to the STL store for no extra charge. There's several travel-savvy employees there who will def. have some good ideas for you. I don't usually shop the Alpine Shop ('cuz I'm down the street from REI), but they'd probably have similar help ideas.

You're gone for a week, right? For me, if I'm only gone for a week, I try at all costs to avoid checking luggage, ESPECIALLY on international flights. If they lose it, it could be near the end of your trip b4 you see it again.

Is your frame remove-able? If so, I've seen people use their backpack and frame as their two carry-ons.

Have you scoped out your pack in terms of the options suggested above for tying up straps, stuffing straps inside, etc. I don't mean to insult your intelligence if you already have...just a thought.