- Bag: Victorinox Standard Issue OR Victorinox Paratrooper
The Standard Issue is a 3-way carry, no wheels bag. It looks like a large laptop bag so I can get away with carrying it into meetings if required and it doesn't look awkward. Paratrooper is a tri-fold garmet bag. Not quite as inconspicuous, light, and versatile as the Standard Issue, but still an effective onebagger.
- Quart-size Ziploc bag
Yes, the one for your 3oz liquids. I pared down my entire toiletry kit to fit into this single bag.
2 Smartphones, 1 tablet, 1 USB wall charger and cable (charges all devices), 1 spare battery for smartphones, 1-pair earbud headphones with microphone (doubles as handsfree headset), Kindle. That's it. I don't use any organizer doo-dads, I just use the organizer pockets in my luggage. Laptop stays behind now most of the time.
- 2 to 3 days worth of clothing
If the trip is 1 week, then I'm going to be washing clothes. Packed clothing has been carefully selected so to maximize versatility for trip settings and clothing outfit combinations.
Try to utilize disposable items where possible. That way if you lose the item, or you have to jettison stuff to make room for those unexpected extra materials you obtained during a meeting on your trip, it's no big deal. Disposable items are not limited just to things that are designed to be disposable, but may also be items that are inexpensive enough that you don't mind replacing them (i.e. inexpensive headphones vs. those expensive Bose models), or items old enough that you don't care if they make it home.
- Make use of things already in your surroundings
Why carry a travel pillow when you can use the ones provided by the airline or you can put a few pairs of your socks rolled into a t-shirt? Why carry tissues when every restroom around you has toilet paper and paper towels? Keep the extra napkins from the lunch you just bought at the terminal food court and stuff them in your pocket for later use. Why carry soap and shampoo when the hotel provides this stuff? You can live without your specialty products for a week. Just pay for a shoe shine or shave along the way instead of carrying shoe polish and a razor. Use the free plastic laundry bags in your hotel room for your dirty clothes instead of carrying a laundry bag. Obtain disposable drinks and water bottles instead of carrying a reusable bottle. Need earplugs? Just tear off a piece of the paper tissue you saved in your pocket. Once you really start looking for it, you'll be surprised what you can find in your immediate surroundings to solve your needs instead of having to carry stuff.
Keep it simple. It's not difficult to do, just requires leaving behind most of the stuff you think you need (but you really don't) and only packing those items that have passed your careful scrutiny after being brutally honest with yourself about what you really need. Remember that worst case, if you find while on your trip there is something you really can't live without, just pull out your credit card and you can easily buy it at your destination. The trick to successfully carrying out a onebag carryon ninja trip has more to do with what you don't bring than what you do bring. Then, make the few items you do bring really count.