Anybody ever read comics with the Flash-- the superhero who was the "fastest man alive?"
The Flash had a ring that held his compressed superhero costume, which would compress again when exposed to a secret gas.
Of course, that would be the UL dream setup. I've seen a lot of threads about using the smallest packs and kits not only to get light, but to get small too. Packs like the REI Flash (odd coincidence, eh?) have been mentioned.
I think I would start with something like a hydration pack and build out from there.
There are some very small and light hydration packs. The Salomon Raid Revo 15 Set has been on my want list for a while. It is just 13 liters-- fine for a day hike. It has big mesh pockets on the front that look like they would swallow up the bulky stuff. Advertised weight is 8 ounces-- I wonder with, or without the bladder and hose?
The other kind of pack that comes to mind is a hydration pack that has a "beavertail" or "shove-it" -- a panel that allows handling a bulky piece of gear with compression straps. Dana built a bunch of larger packs with the ability to add this feature and there are several hydration packs that have one built in. I have a Platypus Typhoon that is a good example. The Typhoon is a lot larger than the Salomon-- 1750 cubic inches -- and it weighs 2 pounds with a bladder and hose.
The Typhoon would be much of a challenge to go super small with. With the beavertail, a waterproof stuff sack could nearly double the storage capacity of the existing pack and only add 4 ounces. That space could be used without the stuff sack, for items like a sleeping pad and rain gear.
So how would you get super small? I'm assuming that would also mean ultra light. Yes, assumptions are dangerous.
I forgot-- a little cheating might be in order. Much like using the waterproof stuff sack outside the pack, a couple pockets added to the waist belt and/or the shoulder straps make sense. I know there are large pockets that go across the chest, but I think they are too hot (and I don't mean sexy).
My idea is to aim for a summer overnighter, with hot meals, and covering all the essentials for safety and survival.
Sleeping bag, pad, and clothing are my primary concerns with size. For a summer overnighter, a 40F bag should be reasonable, so I would use a Mont Bell #7 down bag. The sleeping pad sets me back a little. I have a closed cell foam InsulMat that I like, but it is about 6" x20" rolled on a good day. I have an older Therm-a-Rest pad that will roll up about the size of a Nalgene-- that or something like an uninsulated air mattress. From there it seems to drop to something much more Spartan like a 1/8" foam pad like the ones that Gossamer Gear sells. Add a Mont Bell air pillow to top off the sleeping gear.
Clothing looks like this for a summer overnight trip. I could go three days if I have enough room for food.
REI Sahara zip-off pants
Mont Bell stretch gaiters
Insulation and wind:
Power Stretch 1/2 zip long sleeve tee
Patagonia Micro Puff vest
Montane Aero windshirt
Rain (and shelter):
SMD Gatewood Cape
Other shelter items:
BMW Ti stakes
Trekking poles (in use on the trail)
Spinnsheet ground cloth
AM signal mirror
AM 0.3 first aid kit
Stuff sack for sleeping bag doubles as bear bag
Small line and carabiner for bear bag
Bladder in pack
Aqua Mira for treatment
Mont Bell Ti scoop
Small washcloth/pack towel
Note: all liquids are decanted to small dropper bottles.
Brasslite Ti pot and lid
Ti Esbit wing stove
Foam insulated travel cup with lid
Granola bars, trail mix, instant oatmeal, raisins, snack crackers, dehydrated dinner, candy, coffee, tea, sugar, hot cocoa mix, dried fruit.
I think that's it. I know I could pull it off with the Platypus Typhoon and I just might get away with the Salomon Raid Revo 15, with a few things hanging off the outside-- like an old peddler :)
I could cut back on some of the hygiene for an overnighter, and going cookless would cut some bulk, but that seems to be a shortcut-- gotta have a nice dinner and coffee in the morning.